diff --git a/cel-c/config.h b/cel-c/config.h
index c091c1c..84f5a7f 100644
--- a/cel-c/config.h
+++ b/cel-c/config.h
@@ -26,8 +26,6 @@
 #include <cstddef>      // IWYU pragma: keep
 #include <cstdint>      // IWYU pragma: keep
 #include <cstdlib>      // IWYU pragma: keep
-#include <type_traits>  // IWYU pragma: keep
-#include <utility>      // IWYU pragma: keep
 #ifdef __has_include
 #if __has_include(<version>)
 #include <version>  // IWYU pragma: keep
@@ -84,119 +82,6 @@ CEL_STATIC_ASSERT(sizeof(unsigned char) == 1);
 #define CEL_END_DECLS
 #endif
 
-// cel_typeof/cel_typeof_unqual
-//
-// Expands to `typeof` and `typeof_unqual` equivalents, respectively. In C++
-// mode we remove references which do not exist in C. We also map `char8_t`,
-// `char16_t`, `char32_t`, and `wchar_t` to their respective C types which are
-// aliases of other builtin types instead of distinct types. Additionally we map
-// enums to their underlying type.
-#ifdef __cplusplus
-template <typename T, typename = void>
-struct _cel_typeof {
-  using type = T;
-};
-template <typename T>
-struct _cel_typeof<T, typename std::enable_if<(
-                          std::is_enum<T>::value && !std::is_const<T>::value &&
-                          !std::is_volatile<T>::value)>::type> {
-  using type =
-      typename _cel_typeof<typename std::underlying_type<T>::type>::type;
-};
-template <typename T>
-struct _cel_typeof<T&> {
-  using type = typename _cel_typeof<T>::type;
-};
-template <typename T>
-struct _cel_typeof<T&&> {
-  using type = typename _cel_typeof<T>::type;
-};
-template <typename T>
-struct _cel_typeof<T*> {
-  using type = typename _cel_typeof<T>::type*;
-};
-template <typename T>
-struct _cel_typeof<T[]> {
-  using type = typename _cel_typeof<T>::type[];
-};
-template <typename T>
-struct _cel_typeof<const T[]> {
-  using type = const typename _cel_typeof<T>::type[];
-};
-template <typename T>
-struct _cel_typeof<volatile T[]> {
-  using type = volatile typename _cel_typeof<T>::type[];
-};
-template <typename T>
-struct _cel_typeof<const volatile T[]> {
-  using type = const volatile typename _cel_typeof<T>::type[];
-};
-template <typename T, size_t N>
-struct _cel_typeof<T[N]> {
-  using type = typename _cel_typeof<T>::type[N];
-};
-template <typename T, size_t N>
-struct _cel_typeof<const T[N]> {
-  using type = const typename _cel_typeof<T>::type[N];
-};
-template <typename T, size_t N>
-struct _cel_typeof<volatile T[N]> {
-  using type = volatile typename _cel_typeof<T>::type[N];
-};
-template <typename T, size_t N>
-struct _cel_typeof<const volatile T[N]> {
-  using type = const volatile typename _cel_typeof<T>::type[N];
-};
-template <typename T>
-struct _cel_typeof<const T> {
-  using type = const typename _cel_typeof<T>::type;
-};
-template <typename T>
-struct _cel_typeof<volatile T> {
-  using type = volatile typename _cel_typeof<T>::type;
-};
-template <typename T>
-struct _cel_typeof<const volatile T> {
-  using type = const volatile typename _cel_typeof<T>::type;
-};
-template <>
-struct _cel_typeof<wchar_t> {
-#if defined(__GNUC__) || defined(__clang__)
-  using type = __WCHAR_TYPE__;
-#elif defined(_MSC_VER)
-  using type = unsigned short;  // NOLINT(runtime/int)
-#else
-#error Unexpected compiler.
-#endif
-};
-template <>
-struct _cel_typeof<char16_t> {
-  using type = uint_least16_t;
-};
-template <>
-struct _cel_typeof<char32_t> {
-  using type = uint_least32_t;
-};
-#if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
-template <>
-struct _cel_typeof<char8_t> {
-  using type = unsigned char;
-};
-#endif
-template <typename T>
-struct _cel_typeof_unqual {
-  using type = typename std::remove_cv<typename _cel_typeof<T>::type>::type;
-};
-#define cel_typeof(x) typename ::_cel_typeof<decltype(x)>::type
-#define cel_typeof_unqual(x) typename ::_cel_typeof_unqual<decltype(x)>::type
-#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
-#define cel_typeof(x) typeof(x)
-#define cel_typeof_unqual(x) typeof_unqual(x)
-#else
-#define cel_typeof(x) __typeof__(x)
-#define cel_typeof_unqual(x) __typeof_unqual__(x)
-#endif
-
 #ifdef cel_nullptr
 #error cel_nullptr cannot be directly set
 #endif
@@ -211,32 +96,6 @@ struct _cel_typeof_unqual {
 #define cel_nullptr NULL
 #endif
 
-#ifdef cel_arraysize
-#error cel_arraysize cannot be directly set
-#endif
-
-// cel_arraysize
-//
-// Expands to the number of elements in the array literal.
-#ifdef __cplusplus
-template <typename T, std::size_t N>
-auto _cel_arraysize(const T (&array)[N]) -> char (&)[N];
-#define cel_arraysize(x) (sizeof(::_cel_arraysize((x))))
-#else
-#define cel_arraysize(x) (sizeof((x)) / sizeof((x)[0]))
-#endif
-
-#ifdef cel_containerof
-#error cel_containerof cannot be directly set
-#endif
-
-// cel_containerof
-//
-// Behaves the same as `container_of` in the Linux kernel.
-#define cel_containerof(ptr, type, member)                                    \
-  ((CEL_NULLABILITY_UNKNOWN(type*))(((CEL_NULLABILITY_UNKNOWN(char*))(ptr)) - \
-                                    offsetof(type, member)))
-
 #ifdef CEL_HAVE_BUILTIN
 #error CEL_HAVE_BUILTIN cannot be directly set
 #endif
@@ -702,44 +561,19 @@ auto _cel_arraysize(const T (&array)[N]) -> char (&)[N];
 
 #define cel_kMaxAlign ((size_t)8)
 
-#ifdef _CEL_HAVE_TYPES_COMPATIBLE
-#error _CEL_HAVE_TYPES_COMPATIBLE cannot be directly set
-#endif
-
-#ifdef _CEL_TYPES_COMPATIBLE
-#error _CEL_TYPES_COMPATIBLE cannot be directly set
+#ifdef cel_arraysize
+#error cel_arraysize cannot be directly set
 #endif
 
+// cel_arraysize
+//
+// Expands to the number of elements in the array literal.
 #ifdef __cplusplus
-#define _CEL_HAVE_TYPES_COMPATIBLE 1
-template <typename, typename>
-struct _cel_types_compatible : std::false_type {};
-template <typename T>
-struct _cel_types_compatible<T, T> : std::true_type {};
-template <typename T>
-struct _cel_types_compatible<T[], T[]> : std::true_type {};
-template <typename T, size_t N>
-struct _cel_types_compatible<T[N], T[]> : _cel_types_compatible<T[], T[]> {};
-template <typename T, size_t N>
-struct _cel_types_compatible<T[], T[N]> : _cel_types_compatible<T[], T[]> {};
-#define _CEL_TYPES_COMPATIBLE(type1, type2)                           \
-  ::_cel_types_compatible<typename ::_cel_typeof_unqual<type1>::type, \
-                          typename ::_cel_typeof_unqual<type2>::type>::value
-#elif (defined(__GNUC__) && !defined(__clang__)) || \
-    CEL_HAVE_BUILTIN(__builtin_types_compatible_p)
-#define _CEL_HAVE_TYPES_COMPATIBLE 1
-#define _CEL_TYPES_COMPATIBLE(type1, type2) \
-  __builtin_types_compatible_p(type1, type2)
-#else
-#define _CEL_TYPES_COMPATIBLE(type1, type2) true
-#endif
-
-#ifdef _CEL_HAVE_STMT_EXPRS
-#define _CEL_HAVE_STMT_EXPRS cannot be directly set
-#endif
-
-#if defined(__GNUC__) || defined(__clang__)
-#define _CEL_HAVE_STMT_EXPRS 1
+template <typename T, std::size_t N>
+auto _cel_arraysize(const T (&array)[N]) -> char (&)[N];
+#define cel_arraysize(x) (sizeof(::_cel_arraysize((x))))
+#else
+#define cel_arraysize(x) (sizeof((x)) / sizeof((x)[0]))
 #endif
 
 // We require the standards conforming Microsoft C++ preprocessor.
diff --git a/cel-c/internal/BUILD b/cel-c/internal/BUILD
index 839e880..c35cb69 100644
--- a/cel-c/internal/BUILD
+++ b/cel-c/internal/BUILD
@@ -25,8 +25,8 @@ cc_library(
     hdrs = ["align.h"],
     deps = [
         ":bit",
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -35,7 +35,7 @@ cc_test(
     srcs = ["align_test.cc"],
     deps = [
         ":align",
-        "//cel-c:config",
+        ":config",
         "@googletest//:gtest_main",
     ],
 )
@@ -51,8 +51,8 @@ cc_library(
     srcs = ["any.cc"],
     hdrs = ["any.h"],
     deps = [
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
         "//cel-c:status",
         "//cel-c:status_code",
         "//cel-c:string_view",
@@ -70,9 +70,9 @@ cc_test(
     srcs = ["any_test.cc"],
     deps = [
         ":any",
+        ":config",
         "//cel-c:alloc",
         "//cel-c:arena",
-        "//cel-c:config",
         "//cel-c:status",
         "//cel-c:status_code",
         "//cel-c:string_view",
@@ -98,8 +98,8 @@ cc_library(
     name = "arc",
     hdrs = ["arc.h"],
     deps = [
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -108,7 +108,7 @@ cc_test(
     srcs = ["arc_test.cc"],
     deps = [
         ":arc",
-        "//cel-c:config",
+        ":config",
         "@googletest//:gtest_main",
     ],
 )
@@ -117,9 +117,9 @@ cc_library(
     name = "arena_array",
     hdrs = ["arena_array.h"],
     deps = [
+        ":config",
         ":generic_array",
         "//cel-c:arena",
-        "//cel-c:config",
     ],
 )
 
@@ -128,9 +128,9 @@ cc_test(
     srcs = ["arena_array_test.cc"],
     deps = [
         ":arena_array",
+        ":config",
         "//cel-c:alloc",
         "//cel-c:arena",
-        "//cel-c:config",
         "@abseil-cpp//absl/log:die_if_null",
         "@googletest//:gtest_main",
     ],
@@ -140,9 +140,9 @@ cc_library(
     name = "arena_deque",
     hdrs = ["arena_deque.h"],
     deps = [
+        ":config",
         ":generic_deque",
         "//cel-c:arena",
-        "//cel-c:config",
     ],
 )
 
@@ -151,9 +151,9 @@ cc_test(
     srcs = ["arena_deque_test.cc"],
     deps = [
         ":arena_deque",
+        ":config",
         "//cel-c:alloc",
         "//cel-c:arena",
-        "//cel-c:config",
         "@abseil-cpp//absl/log:die_if_null",
         "@googletest//:gtest_main",
     ],
@@ -163,9 +163,9 @@ cc_library(
     name = "arena_flat_hash_map",
     hdrs = ["arena_flat_hash_map.h"],
     deps = [
+        ":config",
         ":generic_flat_hash",
         "//cel-c:arena",
-        "//cel-c:config",
     ],
 )
 
@@ -174,9 +174,9 @@ cc_test(
     srcs = ["arena_flat_hash_map_test.cc"],
     deps = [
         ":arena_flat_hash_map",
+        ":config",
         "//cel-c:alloc",
         "//cel-c:arena",
-        "//cel-c:config",
         "//cel-c:hash",
         "@abseil-cpp//absl/log:die_if_null",
         "@googletest//:gtest_main",
@@ -187,9 +187,9 @@ cc_library(
     name = "arena_string",
     hdrs = ["arena_string.h"],
     deps = [
+        ":config",
         ":generic_string",
         "//cel-c:arena",
-        "//cel-c:config",
         "//cel-c:cstring_view",
         "//cel-c:string_view",
     ],
@@ -200,10 +200,10 @@ cc_test(
     srcs = ["arena_string_test.cc"],
     deps = [
         ":arena_string",
+        ":config",
         ":generic_string",
         "//cel-c:alloc",
         "//cel-c:arena",
-        "//cel-c:config",
         "//cel-c:cstring_view",
         "//cel-c:string_view",
         "@abseil-cpp//absl/log:die_if_null",
@@ -215,9 +215,9 @@ cc_library(
     name = "array",
     hdrs = ["array.h"],
     deps = [
+        ":config",
         ":generic_array",
         "//cel-c:alloc",
-        "//cel-c:config",
     ],
 )
 
@@ -226,8 +226,8 @@ cc_test(
     srcs = ["array_test.cc"],
     deps = [
         ":array",
+        ":config",
         "//cel-c:alloc",
-        "//cel-c:config",
         "@googletest//:gtest_main",
     ],
 )
@@ -244,8 +244,8 @@ cc_library(
     name = "binary_search",
     hdrs = ["binary_search.h"],
     deps = [
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -263,7 +263,7 @@ cc_library(
     srcs = ["bit.cc"],
     hdrs = ["bit.h"],
     deps = [
-        "//cel-c:config",
+        ":config",
     ],
 )
 
@@ -282,8 +282,8 @@ cc_library(
     hdrs = ["bitset.h"],
     deps = [
         ":bit",
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -305,7 +305,6 @@ cc_library(
         ":config",
         ":ctype",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -322,7 +321,7 @@ cc_library(
     name = "ckdint",
     hdrs = ["ckdint.h"],
     deps = [
-        "//cel-c:config",
+        ":config",
     ],
 )
 
@@ -339,7 +338,7 @@ cc_library(
     name = "compare",
     hdrs = ["compare.h"],
     deps = [
-        "//cel-c:config",
+        ":config",
     ],
 )
 
@@ -355,7 +354,7 @@ cc_test(
     name = "config_test",
     srcs = ["config_test.cc"],
     deps = [
-        "//cel-c:config",
+        ":config",
         "@googletest//:gtest_main",
     ],
 )
@@ -364,10 +363,10 @@ cc_library(
     name = "container",
     hdrs = ["container.h"],
     deps = [
+        ":config",
         ":string",
         "//cel-c:alloc",
         "//cel-c:assert",
-        "//cel-c:config",
         "//cel-c:string_view",
     ],
 )
@@ -390,7 +389,7 @@ cc_library(
     srcs = ["ctype.cc"],
     hdrs = ["ctype.h"],
     deps = [
-        "//cel-c:config",
+        ":config",
     ],
 )
 
@@ -407,9 +406,9 @@ cc_library(
     name = "deque",
     hdrs = ["deque.h"],
     deps = [
+        ":config",
         ":generic_deque",
         "//cel-c:alloc",
-        "//cel-c:config",
     ],
 )
 
@@ -417,9 +416,9 @@ cc_test(
     name = "deque_test",
     srcs = ["deque_test.cc"],
     deps = [
+        ":config",
         ":deque",
         "//cel-c:alloc",
-        "//cel-c:config",
         "@googletest//:gtest_main",
     ],
 )
@@ -447,9 +446,9 @@ cc_library(
     name = "flat_hash_map",
     hdrs = ["flat_hash_map.h"],
     deps = [
+        ":config",
         ":generic_flat_hash",
         "//cel-c:alloc",
-        "//cel-c:config",
     ],
 )
 
@@ -457,9 +456,9 @@ cc_test(
     name = "flat_hash_map_test",
     srcs = ["flat_hash_map_test.cc"],
     deps = [
+        ":config",
         ":flat_hash_map",
         "//cel-c:alloc",
-        "//cel-c:config",
         "//cel-c:hash",
         "@googletest//:gtest_main",
     ],
@@ -469,9 +468,9 @@ cc_library(
     name = "flat_hash_set",
     hdrs = ["flat_hash_set.h"],
     deps = [
+        ":config",
         ":generic_flat_hash",
         "//cel-c:alloc",
-        "//cel-c:config",
     ],
 )
 
@@ -479,9 +478,9 @@ cc_test(
     name = "flat_hash_set_test",
     srcs = ["flat_hash_set_test.cc"],
     deps = [
+        ":config",
         ":flat_hash_set",
         "//cel-c:alloc",
-        "//cel-c:config",
         "//cel-c:hash",
         "@googletest//:gtest_main",
     ],
@@ -508,10 +507,10 @@ cc_library(
     deps = [
         ":align",
         ":asan",
+        ":config",
         "//cel-c:alloc",
         "//cel-c:arena",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -523,10 +522,10 @@ cc_library(
         ":align",
         ":bit",
         ":bitset",
+        ":config",
         "//cel-c:alloc",
         "//cel-c:arena",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -537,10 +536,10 @@ cc_library(
     deps = [
         ":asan",
         ":ckdint",
+        ":config",
         "//cel-c:alloc",
         "//cel-c:arena",
         "//cel-c:assert",
-        "//cel-c:config",
         "//cel-c:cstring_view",
         "//cel-c:string_view",
     ],
@@ -572,8 +571,8 @@ cc_test(
     srcs = ["malloc_test.cc"],
     deps = [
         ":align",
+        ":config",
         ":malloc",
-        "//cel-c:config",
         "@googletest//:gtest_main",
     ],
 )
@@ -604,12 +603,12 @@ cc_library(
     hdrs = ["message_equality.h"],
     deps = [
         ":any",
+        ":config",
         ":number",
         ":setjmp",
         "//cel-c:alloc",
         "//cel-c:arena",
         "//cel-c:assert",
-        "//cel-c:config",
         "//cel-c:string_view",
         "//cel-c:well_known_types",
         "@protobuf//upb/base",
@@ -624,10 +623,10 @@ cc_test(
     name = "message_equality_test",
     srcs = ["message_equality_test.cc"],
     deps = [
+        ":config",
         ":message_equality",
         "//cel-c:alloc",
         "//cel-c:arena",
-        "//cel-c:config",
         "//cel-c:status",
         "//cel-c:well_known_types",
         "@abseil-cpp//absl/base",
@@ -665,8 +664,8 @@ cc_library(
     hdrs = ["number.h"],
     deps = [
         ":compare",
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -684,8 +683,8 @@ cc_library(
     name = "rc",
     hdrs = ["rc.h"],
     deps = [
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -693,8 +692,8 @@ cc_test(
     name = "rc_test",
     srcs = ["rc_test.cc"],
     deps = [
+        ":config",
         ":rc",
-        "//cel-c:config",
         "@googletest//:gtest_main",
     ],
 )
@@ -705,9 +704,9 @@ cc_library(
     hdrs = ["regexp.h"],
     deps = [
         ":alloca",
+        ":config",
         ":malloc",
         "//cel-c:assert",
-        "//cel-c:config",
         "//cel-c:status",
         "//cel-c:status_code",
         "//cel-c:string_view",
@@ -721,8 +720,8 @@ cc_test(
     name = "regexp_test",
     srcs = ["regexp_test.cc"],
     deps = [
+        ":config",
         ":regexp",
-        "//cel-c:config",
         "//cel-c:status",
         "//cel-c:status_code",
         "//cel-c:string_view",
@@ -734,11 +733,11 @@ cc_test(
     name = "runtime_test",
     srcs = ["runtime_test.cc"],
     deps = [
+        ":config",
         ":value",
         "//cel-c:alloc",
         "//cel-c:arena",
         "//cel-c:ast",
-        "//cel-c:config",
         "//cel-c:duration",
         "//cel-c:error",
         "//cel-c:error_code",
@@ -773,7 +772,7 @@ cc_library(
     name = "setjmp",
     hdrs = ["setjmp.h"],
     deps = [
-        "//cel-c:config",
+        ":config",
     ],
 )
 
@@ -791,8 +790,8 @@ cc_library(
     hdrs = ["sort.h"],
     deps = [
         ":alloca",
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -814,8 +813,8 @@ cc_library(
     hdrs = ["stable_sort.h"],
     deps = [
         ":alloca",
+        ":config",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -836,9 +835,9 @@ cc_library(
     name = "string",
     hdrs = ["string.h"],
     deps = [
+        ":config",
         ":generic_string",
         "//cel-c:alloc",
-        "//cel-c:config",
         "//cel-c:cstring_view",
         "//cel-c:string_view",
     ],
@@ -848,10 +847,10 @@ cc_test(
     name = "string_test",
     srcs = ["string_test.cc"],
     deps = [
+        ":config",
         ":generic_string",
         ":string",
         "//cel-c:alloc",
-        "//cel-c:config",
         "//cel-c:cstring_view",
         "//cel-c:string_view",
         "@googletest//:gtest_main",
@@ -862,7 +861,7 @@ cc_test(
     name = "trilean_test",
     srcs = ["trilean_test.cc"],
     deps = [
-        "//cel-c:config",
+        ":config",
         "//cel-c:trilean",
         "@googletest//:gtest_main",
     ],
@@ -872,7 +871,7 @@ cc_library(
     name = "uchar",
     hdrs = ["uchar.h"],
     deps = [
-        "//cel-c:config",
+        ":config",
     ],
 )
 
@@ -883,7 +882,6 @@ cc_library(
         ":config",
         ":endian",
         "//cel-c:assert",
-        "//cel-c:config",
     ],
 )
 
@@ -918,8 +916,8 @@ cc_library(
     name = "unicode",
     hdrs = ["unicode.h"],
     deps = [
+        ":config",
         ":uchar",
-        "//cel-c:config",
     ],
 )
 
@@ -937,10 +935,10 @@ cc_library(
     srcs = ["utf8.cc"],
     hdrs = ["utf8.h"],
     deps = [
+        ":config",
         ":uchar",
         ":unicode",
         "//cel-c:assert",
-        "//cel-c:config",
         "@protobuf//upb/base",
     ],
 )
@@ -990,13 +988,13 @@ cc_library(
         ":bit",
         ":bitset",
         ":ckdint",
+        ":config",
         ":malloc",
         ":message_equality",
         ":sort",
         "//cel-c:alloc",
         "//cel-c:arena",
         "//cel-c:assert",
-        "//cel-c:config",
         "//cel-c:duration",
         "//cel-c:error",
         "//cel-c:error_code",
@@ -1036,9 +1034,9 @@ cc_test(
         "value_test.cc",
     ],
     deps = [
+        ":config",
         ":value",
         ":value_testing",
-        "//cel-c:config",
         "//cel-c:duration",
         "//cel-c:error",
         "//cel-c:error_code",
@@ -1063,9 +1061,9 @@ cc_library(
     srcs = ["value_testing.cc"],
     hdrs = ["value_testing.h"],
     deps = [
+        ":config",
         "//cel-c:alloc",
         "//cel-c:arena",
-        "//cel-c:config",
         "//cel-c:duration",
         "//cel-c:error",
         "//cel-c:status",
@@ -1138,9 +1136,9 @@ cc_library(
     srcs = ["durationconv.cc"],
     hdrs = ["durationconv.h"],
     deps = [
+        ":config",
         "//cel-c:arena",
         "//cel-c:assert",
-        "//cel-c:config",
         "//cel-c:duration",
         "//cel-c:string_view",
         "//cel-c:string_view_absl",
diff --git a/cel-c/internal/align.h b/cel-c/internal/align.h
index 1ce3b9e..2462ead 100644
--- a/cel-c/internal/align.h
+++ b/cel-c/internal/align.h
@@ -24,8 +24,8 @@
 #include <stdint.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/bit.h"
+#include "cel-c/internal/config.h"
 
 // NOLINTBEGIN(runtime/int)
 // NOLINTBEGIN(google-runtime-int)
diff --git a/cel-c/internal/align_test.cc b/cel-c/internal/align_test.cc
index 2be1267..54425d9 100644
--- a/cel-c/internal/align_test.cc
+++ b/cel-c/internal/align_test.cc
@@ -18,7 +18,7 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 // NOLINTBEGIN(runtime/int)
 // NOLINTBEGIN(google-runtime-int)
diff --git a/cel-c/internal/any.cc b/cel-c/internal/any.cc
index 9236562..7c62915 100644
--- a/cel-c/internal/any.cc
+++ b/cel-c/internal/any.cc
@@ -18,7 +18,7 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/status_code.h"
 #include "cel-c/string_view.h"
diff --git a/cel-c/internal/any.h b/cel-c/internal/any.h
index 239cc6a..2fa08bf 100644
--- a/cel-c/internal/any.h
+++ b/cel-c/internal/any.h
@@ -17,7 +17,7 @@
 
 #include <stdbool.h>
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/status_code.h"
 #include "cel-c/well_known_types.h"
diff --git a/cel-c/internal/any_test.cc b/cel-c/internal/any_test.cc
index db3cf57..b7e00b3 100644
--- a/cel-c/internal/any_test.cc
+++ b/cel-c/internal/any_test.cc
@@ -27,7 +27,7 @@
 #include "absl/log/die_if_null.h"
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/status_code.h"
 #include "cel-c/string_view.h"
diff --git a/cel-c/internal/arc.h b/cel-c/internal/arc.h
index 618bfb6..8673d35 100644
--- a/cel-c/internal/arc.h
+++ b/cel-c/internal/arc.h
@@ -32,7 +32,7 @@
 #endif
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 // NOLINTBEGIN(runtime/int)
 // NOLINTBEGIN(google-runtime-int)
diff --git a/cel-c/internal/arc_test.cc b/cel-c/internal/arc_test.cc
index 87e8b9d..ff19cad 100644
--- a/cel-c/internal/arc_test.cc
+++ b/cel-c/internal/arc_test.cc
@@ -16,7 +16,7 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/arena_array.h b/cel-c/internal/arena_array.h
index 7d30f65..e7e984e 100644
--- a/cel-c/internal/arena_array.h
+++ b/cel-c/internal/arena_array.h
@@ -23,7 +23,7 @@
 #include <stddef.h>
 
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_array.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/arena_array_test.cc b/cel-c/internal/arena_array_test.cc
index af5db75..6028715 100644
--- a/cel-c/internal/arena_array_test.cc
+++ b/cel-c/internal/arena_array_test.cc
@@ -21,7 +21,7 @@
 #include "absl/log/die_if_null.h"
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/arena_deque.h b/cel-c/internal/arena_deque.h
index f969169..08ad977 100644
--- a/cel-c/internal/arena_deque.h
+++ b/cel-c/internal/arena_deque.h
@@ -23,7 +23,7 @@
 #include <stddef.h>
 
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_deque.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/arena_deque_test.cc b/cel-c/internal/arena_deque_test.cc
index 6d0ea51..d29507c 100644
--- a/cel-c/internal/arena_deque_test.cc
+++ b/cel-c/internal/arena_deque_test.cc
@@ -22,7 +22,7 @@
 #include "absl/log/die_if_null.h"
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/arena_flat_hash_map.h b/cel-c/internal/arena_flat_hash_map.h
index 23ac9b6..bee0394 100644
--- a/cel-c/internal/arena_flat_hash_map.h
+++ b/cel-c/internal/arena_flat_hash_map.h
@@ -24,7 +24,7 @@
 #include <string.h>
 
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_flat_hash.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/arena_flat_hash_map_test.cc b/cel-c/internal/arena_flat_hash_map_test.cc
index 20c1439..45c1616 100644
--- a/cel-c/internal/arena_flat_hash_map_test.cc
+++ b/cel-c/internal/arena_flat_hash_map_test.cc
@@ -21,8 +21,8 @@
 #include "absl/log/die_if_null.h"
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
 #include "cel-c/hash.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/arena_string.h b/cel-c/internal/arena_string.h
index 1458946..67cafc6 100644
--- a/cel-c/internal/arena_string.h
+++ b/cel-c/internal/arena_string.h
@@ -23,8 +23,8 @@
 #include <stddef.h>
 
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
 #include "cel-c/cstring_view.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_string.h"
 #include "cel-c/string_view.h"
 
diff --git a/cel-c/internal/arena_string_test.cc b/cel-c/internal/arena_string_test.cc
index 7644e7d..7f4ee42 100644
--- a/cel-c/internal/arena_string_test.cc
+++ b/cel-c/internal/arena_string_test.cc
@@ -21,8 +21,8 @@
 #include "absl/log/die_if_null.h"
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
 #include "cel-c/cstring_view.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_string.h"
 #include "cel-c/string_view.h"
 
diff --git a/cel-c/internal/array.h b/cel-c/internal/array.h
index 60db98b..a6d06aa 100644
--- a/cel-c/internal/array.h
+++ b/cel-c/internal/array.h
@@ -23,7 +23,7 @@
 #include <stddef.h>
 
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_array.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/array_test.cc b/cel-c/internal/array_test.cc
index de26c9f..8954be6 100644
--- a/cel-c/internal/array_test.cc
+++ b/cel-c/internal/array_test.cc
@@ -19,7 +19,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/binary_search.h b/cel-c/internal/binary_search.h
index c3a062d..4861872 100644
--- a/cel-c/internal/binary_search.h
+++ b/cel-c/internal/binary_search.h
@@ -19,7 +19,7 @@
 #include <stdint.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/bit.cc b/cel-c/internal/bit.cc
index d0c53ca..8e438be 100644
--- a/cel-c/internal/bit.cc
+++ b/cel-c/internal/bit.cc
@@ -17,7 +17,7 @@
 #include <limits.h>  // IWYU pragma: keep
 #include <stdint.h>  // IWYU pragma: keep
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 #if CEL_HAVE_INCLUDE(<stdbit.h>)
 #include <stdbit.h>
diff --git a/cel-c/internal/bit.h b/cel-c/internal/bit.h
index a4df850..5faeaf3 100644
--- a/cel-c/internal/bit.h
+++ b/cel-c/internal/bit.h
@@ -22,7 +22,7 @@
 #include <limits.h>   // IWYU pragma: keep
 #include <stdbool.h>  // IWYU pragma: keep
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 #if CEL_HAVE_INCLUDE(<stdbit.h>)
 #include <stdbit.h>
diff --git a/cel-c/internal/bitset.cc b/cel-c/internal/bitset.cc
index f3a1f64..82c7a5f 100644
--- a/cel-c/internal/bitset.cc
+++ b/cel-c/internal/bitset.cc
@@ -18,8 +18,8 @@
 #include <stddef.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/bit.h"
+#include "cel-c/internal/config.h"
 
 extern "C" bool _cel_BitSet_Next(CEL_NULLABLE(const _cel_BitSetWord*) words,
                                  size_t bits, CEL_NONNULL(size_t*) bit) {
diff --git a/cel-c/internal/bitset.h b/cel-c/internal/bitset.h
index 9b27045..cae3aa9 100644
--- a/cel-c/internal/bitset.h
+++ b/cel-c/internal/bitset.h
@@ -22,7 +22,7 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/charconv.cc b/cel-c/internal/charconv.cc
index 95dc257..721bc5a 100644
--- a/cel-c/internal/charconv.cc
+++ b/cel-c/internal/charconv.cc
@@ -24,7 +24,6 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/ckdint.h"
 #include "cel-c/internal/config.h"
 #include "cel-c/internal/ctype.h"
diff --git a/cel-c/internal/ckdint.h b/cel-c/internal/ckdint.h
index bf062c5..f9d8062 100644
--- a/cel-c/internal/ckdint.h
+++ b/cel-c/internal/ckdint.h
@@ -22,7 +22,7 @@
 #include <limits.h>
 #include <stdbool.h>  // IWYU pragma: keep
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 #if CEL_HAVE_INCLUDE(<stdckdint.h>)
 #include <stdckdint.h>
diff --git a/cel-c/internal/compare.h b/cel-c/internal/compare.h
index cc7036e..4b3ffac 100644
--- a/cel-c/internal/compare.h
+++ b/cel-c/internal/compare.h
@@ -15,7 +15,7 @@
 #ifndef THIRD_PARTY_CEL_C_INTERNAL_COMPARE_H_
 #define THIRD_PARTY_CEL_C_INTERNAL_COMPARE_H_
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/config.h b/cel-c/internal/config.h
index 8be8120..02edebd 100644
--- a/cel-c/internal/config.h
+++ b/cel-c/internal/config.h
@@ -17,6 +17,10 @@
 #ifndef THIRD_PARTY_CEL_C_INTERNAL_CONFIG_H_
 #define THIRD_PARTY_CEL_C_INTERNAL_CONFIG_H_
 
+#include <cstddef>
+#include <cstdint>
+#include <type_traits>
+
 #include "cel-c/config.h"  // IWYU pragma: export
 
 #if defined(__BIG_ENDIAN__) || defined(__ARMEB__) || defined(__THUMBEB__) || \
@@ -135,4 +139,160 @@
 #define _CEL_HAVE_SANITIZER 1
 #endif
 
+// cel_typeof/cel_typeof_unqual
+//
+// Expands to `typeof` and `typeof_unqual` equivalents, respectively. In C++
+// mode we remove references which do not exist in C. We also map `char8_t`,
+// `char16_t`, `char32_t`, and `wchar_t` to their respective C types which are
+// aliases of other builtin types instead of distinct types. Additionally we map
+// enums to their underlying type.
+#ifdef __cplusplus
+template <typename T, typename = void>
+struct _cel_typeof {
+  using type = T;
+};
+template <typename T>
+struct _cel_typeof<T, typename std::enable_if<(
+                          std::is_enum<T>::value && !std::is_const<T>::value &&
+                          !std::is_volatile<T>::value)>::type> {
+  using type =
+      typename _cel_typeof<typename std::underlying_type<T>::type>::type;
+};
+template <typename T>
+struct _cel_typeof<T&> {
+  using type = typename _cel_typeof<T>::type;
+};
+template <typename T>
+struct _cel_typeof<T&&> {
+  using type = typename _cel_typeof<T>::type;
+};
+template <typename T>
+struct _cel_typeof<T*> {
+  using type = typename _cel_typeof<T>::type*;
+};
+template <typename T>
+struct _cel_typeof<T[]> {
+  using type = typename _cel_typeof<T>::type[];
+};
+template <typename T>
+struct _cel_typeof<const T[]> {
+  using type = const typename _cel_typeof<T>::type[];
+};
+template <typename T>
+struct _cel_typeof<volatile T[]> {
+  using type = volatile typename _cel_typeof<T>::type[];
+};
+template <typename T>
+struct _cel_typeof<const volatile T[]> {
+  using type = const volatile typename _cel_typeof<T>::type[];
+};
+template <typename T, size_t N>
+struct _cel_typeof<T[N]> {
+  using type = typename _cel_typeof<T>::type[N];
+};
+template <typename T, size_t N>
+struct _cel_typeof<const T[N]> {
+  using type = const typename _cel_typeof<T>::type[N];
+};
+template <typename T, size_t N>
+struct _cel_typeof<volatile T[N]> {
+  using type = volatile typename _cel_typeof<T>::type[N];
+};
+template <typename T, size_t N>
+struct _cel_typeof<const volatile T[N]> {
+  using type = const volatile typename _cel_typeof<T>::type[N];
+};
+template <typename T>
+struct _cel_typeof<const T> {
+  using type = const typename _cel_typeof<T>::type;
+};
+template <typename T>
+struct _cel_typeof<volatile T> {
+  using type = volatile typename _cel_typeof<T>::type;
+};
+template <typename T>
+struct _cel_typeof<const volatile T> {
+  using type = const volatile typename _cel_typeof<T>::type;
+};
+template <>
+struct _cel_typeof<wchar_t> {
+#if defined(__GNUC__) || defined(__clang__)
+  using type = __WCHAR_TYPE__;
+#elif defined(_MSC_VER)
+  using type = unsigned short;  // NOLINT(runtime/int)
+#else
+#error Unexpected compiler.
+#endif
+};
+template <>
+struct _cel_typeof<char16_t> {
+  using type = uint_least16_t;
+};
+template <>
+struct _cel_typeof<char32_t> {
+  using type = uint_least32_t;
+};
+#if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
+template <>
+struct _cel_typeof<char8_t> {
+  using type = unsigned char;
+};
+#endif
+template <typename T>
+struct _cel_typeof_unqual {
+  using type = typename std::remove_cv<typename _cel_typeof<T>::type>::type;
+};
+#define cel_typeof(x) typename ::_cel_typeof<decltype(x)>::type
+#define cel_typeof_unqual(x) typename ::_cel_typeof_unqual<decltype(x)>::type
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
+#define cel_typeof(x) typeof(x)
+#define cel_typeof_unqual(x) typeof_unqual(x)
+#else
+#define cel_typeof(x) __typeof__(x)
+#define cel_typeof_unqual(x) __typeof_unqual__(x)
+#endif
+
+#ifdef cel_containerof
+#error cel_containerof cannot be directly set
+#endif
+
+// cel_containerof
+//
+// Behaves the same as `container_of` in the Linux kernel.
+#define cel_containerof(ptr, type, member)                                    \
+  ((CEL_NULLABILITY_UNKNOWN(type*))(((CEL_NULLABILITY_UNKNOWN(char*))(ptr)) - \
+                                    offsetof(type, member)))
+
+#ifdef _CEL_HAVE_TYPES_COMPATIBLE
+#error _CEL_HAVE_TYPES_COMPATIBLE cannot be directly set
+#endif
+
+#ifdef _CEL_TYPES_COMPATIBLE
+#error _CEL_TYPES_COMPATIBLE cannot be directly set
+#endif
+
+#ifdef __cplusplus
+#define _CEL_HAVE_TYPES_COMPATIBLE 1
+template <typename, typename>
+struct _cel_types_compatible : std::false_type {};
+template <typename T>
+struct _cel_types_compatible<T, T> : std::true_type {};
+template <typename T>
+struct _cel_types_compatible<T[], T[]> : std::true_type {};
+template <typename T, size_t N>
+struct _cel_types_compatible<T[N], T[]> : _cel_types_compatible<T[], T[]> {};
+template <typename T, size_t N>
+struct _cel_types_compatible<T[], T[N]> : _cel_types_compatible<T[], T[]> {};
+#define _CEL_TYPES_COMPATIBLE(type1, type2)                           \
+  ::_cel_types_compatible<typename ::_cel_typeof_unqual<type1>::type, \
+                          typename ::_cel_typeof_unqual<type2>::type>::value
+#elif (defined(__GNUC__) && !defined(__clang__)) || \
+    CEL_HAVE_BUILTIN(__builtin_types_compatible_p)
+#define _CEL_HAVE_TYPES_COMPATIBLE 1
+#define _CEL_TYPES_COMPATIBLE(type1, type2) \
+  __builtin_types_compatible_p(type1, type2)
+#else
+#define _CEL_TYPES_COMPATIBLE(type1, type2) true
+#endif
+
 #endif  // THIRD_PARTY_CEL_C_INTERNAL_CONFIG_H_
diff --git a/cel-c/internal/config_test.cc b/cel-c/internal/config_test.cc
index f9bb466..e83dd71 100644
--- a/cel-c/internal/config_test.cc
+++ b/cel-c/internal/config_test.cc
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 #include <cstdint>
 #include <type_traits>
diff --git a/cel-c/internal/container.h b/cel-c/internal/container.h
index bbf3d5d..2028cda 100644
--- a/cel-c/internal/container.h
+++ b/cel-c/internal/container.h
@@ -19,7 +19,7 @@
 
 #include "cel-c/alloc.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/string.h"
 #include "cel-c/string_view.h"
 
diff --git a/cel-c/internal/ctype.h b/cel-c/internal/ctype.h
index 7909223..ba9589d 100644
--- a/cel-c/internal/ctype.h
+++ b/cel-c/internal/ctype.h
@@ -17,7 +17,7 @@
 
 #include <stdbool.h>
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/deque.h b/cel-c/internal/deque.h
index 9878dac..706d3bb 100644
--- a/cel-c/internal/deque.h
+++ b/cel-c/internal/deque.h
@@ -23,7 +23,7 @@
 #include <stddef.h>
 
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_deque.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/deque_test.cc b/cel-c/internal/deque_test.cc
index e8973cd..40be60d 100644
--- a/cel-c/internal/deque_test.cc
+++ b/cel-c/internal/deque_test.cc
@@ -20,7 +20,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/durationconv.cc b/cel-c/internal/durationconv.cc
index 3d013fa..e72c03d 100644
--- a/cel-c/internal/durationconv.cc
+++ b/cel-c/internal/durationconv.cc
@@ -23,8 +23,8 @@
 #include "absl/time/time.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/duration.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 #include "cel-c/string_view_absl.h"
 
diff --git a/cel-c/internal/durationconv.h b/cel-c/internal/durationconv.h
index f0229ae..a1fa36d 100644
--- a/cel-c/internal/durationconv.h
+++ b/cel-c/internal/durationconv.h
@@ -16,8 +16,8 @@
 #define THIRD_PARTY_CEL_C_INTERNAL_DURATIONCONV_H_
 
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
 #include "cel-c/duration.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 
 // NOLINTBEGIN(runtime/int)
diff --git a/cel-c/internal/empty_list_value.cc b/cel-c/internal/empty_list_value.cc
index 1bc004b..22df8fb 100644
--- a/cel-c/internal/empty_list_value.cc
+++ b/cel-c/internal/empty_list_value.cc
@@ -20,9 +20,9 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
 #include "cel-c/value.h"
diff --git a/cel-c/internal/empty_list_value.h b/cel-c/internal/empty_list_value.h
index 0b002cf..1646eb9 100644
--- a/cel-c/internal/empty_list_value.h
+++ b/cel-c/internal/empty_list_value.h
@@ -16,7 +16,7 @@
 #define THIRD_PARTY_CEL_C_INTERNAL_EMPTY_LIST_VALUE_H_
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/value.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/empty_map_value.cc b/cel-c/internal/empty_map_value.cc
index bac17ae..8944b3b 100644
--- a/cel-c/internal/empty_map_value.cc
+++ b/cel-c/internal/empty_map_value.cc
@@ -20,9 +20,9 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
 #include "cel-c/value.h"
diff --git a/cel-c/internal/empty_map_value.h b/cel-c/internal/empty_map_value.h
index 4a96fa1..b2930cb 100644
--- a/cel-c/internal/empty_map_value.h
+++ b/cel-c/internal/empty_map_value.h
@@ -16,7 +16,7 @@
 #define THIRD_PARTY_CEL_C_INTERNAL_EMPTY_MAP_VALUE_H_
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/value.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/flat_hash_map.h b/cel-c/internal/flat_hash_map.h
index 49ad5b7..1576afa 100644
--- a/cel-c/internal/flat_hash_map.h
+++ b/cel-c/internal/flat_hash_map.h
@@ -24,7 +24,7 @@
 #include <string.h>
 
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_flat_hash.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/flat_hash_map_test.cc b/cel-c/internal/flat_hash_map_test.cc
index 28dd708..1d7df67 100644
--- a/cel-c/internal/flat_hash_map_test.cc
+++ b/cel-c/internal/flat_hash_map_test.cc
@@ -19,8 +19,8 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
 #include "cel-c/hash.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/flat_hash_set.h b/cel-c/internal/flat_hash_set.h
index 64cdeaa..a580d6b 100644
--- a/cel-c/internal/flat_hash_set.h
+++ b/cel-c/internal/flat_hash_set.h
@@ -24,7 +24,7 @@
 #include <string.h>
 
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_flat_hash.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/flat_hash_set_test.cc b/cel-c/internal/flat_hash_set_test.cc
index e86602c..aac4431 100644
--- a/cel-c/internal/flat_hash_set_test.cc
+++ b/cel-c/internal/flat_hash_set_test.cc
@@ -19,8 +19,8 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
 #include "cel-c/hash.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/generic_deque.cc b/cel-c/internal/generic_deque.cc
index 310b18e..a8d27b6 100644
--- a/cel-c/internal/generic_deque.cc
+++ b/cel-c/internal/generic_deque.cc
@@ -22,9 +22,9 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/align.h"
 #include "cel-c/internal/asan.h"
+#include "cel-c/internal/config.h"
 
 typedef struct _cel_GenericDequeBlock _cel_GenericDequeBlock;
 
diff --git a/cel-c/internal/generic_deque.h b/cel-c/internal/generic_deque.h
index 62f0411..f80d944 100644
--- a/cel-c/internal/generic_deque.h
+++ b/cel-c/internal/generic_deque.h
@@ -26,7 +26,7 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/generic_flat_hash.cc b/cel-c/internal/generic_flat_hash.cc
index b9a013f..2580724 100644
--- a/cel-c/internal/generic_flat_hash.cc
+++ b/cel-c/internal/generic_flat_hash.cc
@@ -24,10 +24,10 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/align.h"
 #include "cel-c/internal/bit.h"
 #include "cel-c/internal/bitset.h"
+#include "cel-c/internal/config.h"
 
 CEL_ATTRIBUTE_NODISCARD
 static size_t _cel_GenericFlatHash_Rehash(
diff --git a/cel-c/internal/generic_flat_hash.h b/cel-c/internal/generic_flat_hash.h
index dc5b04f..0142655 100644
--- a/cel-c/internal/generic_flat_hash.h
+++ b/cel-c/internal/generic_flat_hash.h
@@ -26,8 +26,8 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/bitset.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/generic_string.cc b/cel-c/internal/generic_string.cc
index 94bb64f..020f432 100644
--- a/cel-c/internal/generic_string.cc
+++ b/cel-c/internal/generic_string.cc
@@ -26,9 +26,9 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/asan.h"
 #include "cel-c/internal/ckdint.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 
 static void _cel_GenericString_AnnotateNew(CEL_NONNULL(char*) str, size_t len,
diff --git a/cel-c/internal/generic_string.h b/cel-c/internal/generic_string.h
index eb49244..0ec3b82 100644
--- a/cel-c/internal/generic_string.h
+++ b/cel-c/internal/generic_string.h
@@ -29,8 +29,8 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/cstring_view.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/list_value.cc b/cel-c/internal/list_value.cc
index b188ba6..f616cdb 100644
--- a/cel-c/internal/list_value.cc
+++ b/cel-c/internal/list_value.cc
@@ -18,7 +18,7 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/value.h"
 
diff --git a/cel-c/internal/list_value_test.cc b/cel-c/internal/list_value_test.cc
index 43dede0..195aad2 100644
--- a/cel-c/internal/list_value_test.cc
+++ b/cel-c/internal/list_value_test.cc
@@ -15,9 +15,9 @@
 #include <cstddef>
 
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/empty_list_value.h"
 #include "cel-c/internal/value_testing.h"
 #include "cel-c/status.h"
diff --git a/cel-c/internal/malloc_test.cc b/cel-c/internal/malloc_test.cc
index f23a70c..1eab7f8 100644
--- a/cel-c/internal/malloc_test.cc
+++ b/cel-c/internal/malloc_test.cc
@@ -19,8 +19,8 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/align.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/map_value.cc b/cel-c/internal/map_value.cc
index e7eefdd..a2a2b49 100644
--- a/cel-c/internal/map_value.cc
+++ b/cel-c/internal/map_value.cc
@@ -20,8 +20,8 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/array.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/sort.h"
 #include "cel-c/status.h"
 #include "cel-c/value.h"
diff --git a/cel-c/internal/map_value.h b/cel-c/internal/map_value.h
index bbdb98b..74a4b69 100644
--- a/cel-c/internal/map_value.h
+++ b/cel-c/internal/map_value.h
@@ -17,8 +17,8 @@
 
 #include <stdint.h>
 
-#include "cel-c/config.h"
 #include "cel-c/hash.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 #include "cel-c/value.h"
 #include "upb/base/descriptor_constants.h"
diff --git a/cel-c/internal/map_value_test.cc b/cel-c/internal/map_value_test.cc
index 3afb4ae..6e9a527 100644
--- a/cel-c/internal/map_value_test.cc
+++ b/cel-c/internal/map_value_test.cc
@@ -19,10 +19,10 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
 #include "cel-c/hash.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/empty_map_value.h"
 #include "cel-c/internal/value_testing.h"
 #include "cel-c/status.h"
diff --git a/cel-c/internal/message_equality.cc b/cel-c/internal/message_equality.cc
index 899eb49..8d3f0a7 100644
--- a/cel-c/internal/message_equality.cc
+++ b/cel-c/internal/message_equality.cc
@@ -21,8 +21,8 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/any.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/number.h"
 #include "cel-c/internal/setjmp.h"
 #include "cel-c/string_view.h"
diff --git a/cel-c/internal/message_equality.h b/cel-c/internal/message_equality.h
index bfcb082..d2174fd 100644
--- a/cel-c/internal/message_equality.h
+++ b/cel-c/internal/message_equality.h
@@ -18,7 +18,7 @@
 #include <stdbool.h>
 
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/well_known_types.h"
 #include "upb/message/array.h"
 #include "upb/message/message.h"
diff --git a/cel-c/internal/message_equality_test.cc b/cel-c/internal/message_equality_test.cc
index 6362d78..ace2d46 100644
--- a/cel-c/internal/message_equality_test.cc
+++ b/cel-c/internal/message_equality_test.cc
@@ -41,7 +41,7 @@
 #include "absl/types/variant.h"
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/well_known_types.h"
 #include "cel/expr/conformance/proto3/test_all_types.pb.h"
diff --git a/cel-c/internal/mutable_list_value.cc b/cel-c/internal/mutable_list_value.cc
index 5ac7ae8..b07a776 100644
--- a/cel-c/internal/mutable_list_value.cc
+++ b/cel-c/internal/mutable_list_value.cc
@@ -22,10 +22,10 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
 #include "cel-c/internal/ckdint.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/empty_list_value.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
diff --git a/cel-c/internal/mutable_list_value.h b/cel-c/internal/mutable_list_value.h
index 84978bf..fc6adf1 100644
--- a/cel-c/internal/mutable_list_value.h
+++ b/cel-c/internal/mutable_list_value.h
@@ -20,7 +20,7 @@
 
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/value.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/mutable_map_value.cc b/cel-c/internal/mutable_map_value.cc
index 8911c99..9d97bfd 100644
--- a/cel-c/internal/mutable_map_value.cc
+++ b/cel-c/internal/mutable_map_value.cc
@@ -23,11 +23,11 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
 #include "cel-c/hash.h"
 #include "cel-c/internal/bit.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/empty_map_value.h"
 #include "cel-c/internal/map_value.h"
 #include "cel-c/status.h"
diff --git a/cel-c/internal/mutable_map_value.h b/cel-c/internal/mutable_map_value.h
index d8f65b7..22a28bc 100644
--- a/cel-c/internal/mutable_map_value.h
+++ b/cel-c/internal/mutable_map_value.h
@@ -20,7 +20,7 @@
 
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/value.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/number.h b/cel-c/internal/number.h
index 2db1873..6a33b28 100644
--- a/cel-c/internal/number.h
+++ b/cel-c/internal/number.h
@@ -22,8 +22,8 @@
 #include <stdint.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/compare.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/opaque_value.cc b/cel-c/internal/opaque_value.cc
index 822fa3a..88bef18 100644
--- a/cel-c/internal/opaque_value.cc
+++ b/cel-c/internal/opaque_value.cc
@@ -17,7 +17,7 @@
 #include <stdlib.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
 #include "cel-c/value.h"
diff --git a/cel-c/internal/opaque_value_test.cc b/cel-c/internal/opaque_value_test.cc
index f81fbba..3b1fadc 100644
--- a/cel-c/internal/opaque_value_test.cc
+++ b/cel-c/internal/opaque_value_test.cc
@@ -13,7 +13,7 @@
 // limitations under the License.
 
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/value_testing.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
diff --git a/cel-c/internal/optional_value.cc b/cel-c/internal/optional_value.cc
index 23ad29a..f456992 100644
--- a/cel-c/internal/optional_value.cc
+++ b/cel-c/internal/optional_value.cc
@@ -18,10 +18,10 @@
 
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/duration.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
 #include "cel-c/timestamp.h"
diff --git a/cel-c/internal/parsed_map_field_value.cc b/cel-c/internal/parsed_map_field_value.cc
index 8bf7d81..1050064 100644
--- a/cel-c/internal/parsed_map_field_value.cc
+++ b/cel-c/internal/parsed_map_field_value.cc
@@ -21,9 +21,9 @@
 
 #include "cel-c/alloc.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/map_value.h"
 #include "cel-c/internal/message_equality.h"
 #include "cel-c/status.h"
diff --git a/cel-c/internal/parsed_map_field_value.h b/cel-c/internal/parsed_map_field_value.h
index 41a2706..1e5db57 100644
--- a/cel-c/internal/parsed_map_field_value.h
+++ b/cel-c/internal/parsed_map_field_value.h
@@ -16,7 +16,7 @@
 #define THIRD_PARTY_CEL_C_INTERNAL_PARSED_MAP_FIELD_VALUE_H_
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/empty_map_value.h"
 #include "cel-c/value.h"
 #include "upb/message/map.h"
diff --git a/cel-c/internal/parsed_message_value.cc b/cel-c/internal/parsed_message_value.cc
index ce077c6..fd69717 100644
--- a/cel-c/internal/parsed_message_value.cc
+++ b/cel-c/internal/parsed_message_value.cc
@@ -21,9 +21,9 @@
 
 #include "cel-c/alloc.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/message_equality.h"
 #include "cel-c/status.h"
 #include "cel-c/status_code.h"
diff --git a/cel-c/internal/parsed_message_value.h b/cel-c/internal/parsed_message_value.h
index 9a4b886..e5a2783 100644
--- a/cel-c/internal/parsed_message_value.h
+++ b/cel-c/internal/parsed_message_value.h
@@ -16,7 +16,7 @@
 #define THIRD_PARTY_CEL_C_INTERNAL_PARSED_MESSAGE_VALUE_H_
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/type.h"
 #include "cel-c/value.h"
 #include "upb/message/message.h"
diff --git a/cel-c/internal/parsed_repeated_field_value.cc b/cel-c/internal/parsed_repeated_field_value.cc
index 2defeb9..d2bcee0 100644
--- a/cel-c/internal/parsed_repeated_field_value.cc
+++ b/cel-c/internal/parsed_repeated_field_value.cc
@@ -21,9 +21,9 @@
 
 #include "cel-c/alloc.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/message_equality.h"
 #include "cel-c/status.h"
 #include "cel-c/status_code.h"
diff --git a/cel-c/internal/parsed_repeated_field_value.h b/cel-c/internal/parsed_repeated_field_value.h
index 669ab76..3d5075a 100644
--- a/cel-c/internal/parsed_repeated_field_value.h
+++ b/cel-c/internal/parsed_repeated_field_value.h
@@ -16,7 +16,7 @@
 #define THIRD_PARTY_CEL_C_INTERNAL_PARSED_REPEATED_FIELD_VALUE_H_
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/empty_list_value.h"
 #include "cel-c/value.h"
 #include "upb/message/array.h"
diff --git a/cel-c/internal/rc.h b/cel-c/internal/rc.h
index 317138f..e7a3ef7 100644
--- a/cel-c/internal/rc.h
+++ b/cel-c/internal/rc.h
@@ -21,7 +21,7 @@
 #include <stdbool.h>  // IWYU pragma: keep
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 // NOLINTBEGIN(runtime/int)
 // NOLINTBEGIN(google-runtime-int)
diff --git a/cel-c/internal/rc_test.cc b/cel-c/internal/rc_test.cc
index ea9721a..5e365a1 100644
--- a/cel-c/internal/rc_test.cc
+++ b/cel-c/internal/rc_test.cc
@@ -16,7 +16,7 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/regexp.cc b/cel-c/internal/regexp.cc
index 290262e..c36a429 100644
--- a/cel-c/internal/regexp.cc
+++ b/cel-c/internal/regexp.cc
@@ -21,8 +21,8 @@
 
 #include "absl/strings/string_view.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/alloca.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/malloc.h"
 #include "cel-c/status.h"
 #include "cel-c/status_code.h"
diff --git a/cel-c/internal/regexp.h b/cel-c/internal/regexp.h
index a496675..7ed736a 100644
--- a/cel-c/internal/regexp.h
+++ b/cel-c/internal/regexp.h
@@ -19,7 +19,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
 
diff --git a/cel-c/internal/regexp_test.cc b/cel-c/internal/regexp_test.cc
index c982ec7..ac69c23 100644
--- a/cel-c/internal/regexp_test.cc
+++ b/cel-c/internal/regexp_test.cc
@@ -18,7 +18,7 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/status_code.h"
 #include "cel-c/string_view.h"
diff --git a/cel-c/internal/runtime/BUILD b/cel-c/internal/runtime/BUILD
index 3484534..1f23a78 100644
--- a/cel-c/internal/runtime/BUILD
+++ b/cel-c/internal/runtime/BUILD
@@ -43,7 +43,6 @@ cc_library(
         "//cel-c:ast",
         "//cel-c:ast_traverse",
         "//cel-c:ast_visitor",
-        "//cel-c:config",
         "//cel-c:constant",
         "//cel-c:duration",
         "//cel-c:error",
diff --git a/cel-c/internal/runtime/activation.cc b/cel-c/internal/runtime/activation.cc
index e5cfa17..f446e10 100644
--- a/cel-c/internal/runtime/activation.cc
+++ b/cel-c/internal/runtime/activation.cc
@@ -21,7 +21,7 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/runtime/instr.h"
 #include "cel-c/internal/runtime/interpretable.h"
 #include "cel-c/internal/runtime/program.h"
diff --git a/cel-c/internal/runtime/activation.h b/cel-c/internal/runtime/activation.h
index 77b0f63..8e52c05 100644
--- a/cel-c/internal/runtime/activation.h
+++ b/cel-c/internal/runtime/activation.h
@@ -21,7 +21,7 @@
 #include "cel-c/activation.h"  // IWYU pragma: export
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/runtime/instr.h"
 #include "cel-c/internal/runtime/interpretable.h"
 #include "cel-c/program.h"
diff --git a/cel-c/internal/runtime/instr.h b/cel-c/internal/runtime/instr.h
index 107a24b..22f0fd1 100644
--- a/cel-c/internal/runtime/instr.h
+++ b/cel-c/internal/runtime/instr.h
@@ -19,8 +19,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "cel-c/config.h"
 #include "cel-c/duration.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 #include "cel-c/timestamp.h"
 #include "upb/reflection/def.h"
diff --git a/cel-c/internal/runtime/interpretable.cc b/cel-c/internal/runtime/interpretable.cc
index 38b903d..3bc4748 100644
--- a/cel-c/internal/runtime/interpretable.cc
+++ b/cel-c/internal/runtime/interpretable.cc
@@ -25,7 +25,6 @@
 #include "cel-c/activation.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/duration.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
diff --git a/cel-c/internal/runtime/interpretable.h b/cel-c/internal/runtime/interpretable.h
index 640b882..0584bc6 100644
--- a/cel-c/internal/runtime/interpretable.h
+++ b/cel-c/internal/runtime/interpretable.h
@@ -21,7 +21,7 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/runtime/instr.h"
 #include "cel-c/internal/runtime/program.h"
 #include "cel-c/internal/setjmp.h"
diff --git a/cel-c/internal/runtime/interpreter.cc b/cel-c/internal/runtime/interpreter.cc
index 0deb6ff..b91655f 100644
--- a/cel-c/internal/runtime/interpreter.cc
+++ b/cel-c/internal/runtime/interpreter.cc
@@ -23,10 +23,10 @@
 #include "cel-c/ast.h"
 #include "cel-c/ast_traverse.h"
 #include "cel-c/ast_visitor.h"
-#include "cel-c/config.h"
 #include "cel-c/constant.h"
 #include "cel-c/hash.h"
 #include "cel-c/internal/array.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/container.h"
 #include "cel-c/internal/deque.h"
 #include "cel-c/internal/flat_hash_map.h"
diff --git a/cel-c/internal/runtime/interpreter.h b/cel-c/internal/runtime/interpreter.h
index fe9bbec..ed31295 100644
--- a/cel-c/internal/runtime/interpreter.h
+++ b/cel-c/internal/runtime/interpreter.h
@@ -16,7 +16,7 @@
 #define THIRD_PARTY_CEL_C_INTERNAL_RUNTIME_INTERPRETER_H_
 
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/runtime/program.h"
 #include "cel-c/internal/runtime/runtime.h"
 #include "cel-c/status.h"
diff --git a/cel-c/internal/runtime/program.cc b/cel-c/internal/runtime/program.cc
index a25bd0c..5889e73 100644
--- a/cel-c/internal/runtime/program.cc
+++ b/cel-c/internal/runtime/program.cc
@@ -19,9 +19,9 @@
 
 #include "cel-c/alloc.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/arc.h"
 #include "cel-c/internal/array.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/runtime/activation.h"
 #include "cel-c/internal/runtime/runtime.h"
 #include "cel-c/internal/string.h"
diff --git a/cel-c/internal/runtime/program.h b/cel-c/internal/runtime/program.h
index 1c7a57b..6ab1305 100644
--- a/cel-c/internal/runtime/program.h
+++ b/cel-c/internal/runtime/program.h
@@ -20,9 +20,9 @@
 #include <string.h>
 
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/arc.h"
 #include "cel-c/internal/array.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/runtime/instr.h"
 #include "cel-c/internal/string.h"
 #include "cel-c/program.h"  // IWYU pragma: export
diff --git a/cel-c/internal/runtime/runtime.cc b/cel-c/internal/runtime/runtime.cc
index db22da4..908937a 100644
--- a/cel-c/internal/runtime/runtime.cc
+++ b/cel-c/internal/runtime/runtime.cc
@@ -19,8 +19,8 @@
 #include "cel-c/alloc.h"
 #include "cel-c/assert.h"
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/arc.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/container.h"
 #include "cel-c/internal/runtime/interpreter.h"
 #include "cel-c/internal/string.h"
diff --git a/cel-c/internal/runtime/runtime.h b/cel-c/internal/runtime/runtime.h
index 4f5ac93..5d00b8d 100644
--- a/cel-c/internal/runtime/runtime.h
+++ b/cel-c/internal/runtime/runtime.h
@@ -16,8 +16,8 @@
 #define THIRD_PARTY_CEL_C_INTERNAL_RUNTIME_RUNTIME_H_
 
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/arc.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/container.h"
 #include "cel-c/runtime.h"  // IWYU pragma: export
 #include "cel-c/well_known_types.h"
diff --git a/cel-c/internal/runtime_test.cc b/cel-c/internal/runtime_test.cc
index 2e59d87..9611abf 100644
--- a/cel-c/internal/runtime_test.cc
+++ b/cel-c/internal/runtime_test.cc
@@ -32,10 +32,10 @@
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
 #include "cel-c/duration.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/parsed_map_field_value.h"
 #include "cel-c/internal/runtime/program.h"
 #include "cel-c/internal/testing/compiler.h"
diff --git a/cel-c/internal/setjmp.h b/cel-c/internal/setjmp.h
index 4589fe2..eae6aaf 100644
--- a/cel-c/internal/setjmp.h
+++ b/cel-c/internal/setjmp.h
@@ -21,7 +21,7 @@
 
 #include <setjmp.h>  // IWYU pragma: keep
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 #if CEL_HAVE_INCLUDE(<unistd.h>)
 // Include <unistd.h> for _POSIX_VERSION.
diff --git a/cel-c/internal/sort.h b/cel-c/internal/sort.h
index 6428055..542b962 100644
--- a/cel-c/internal/sort.h
+++ b/cel-c/internal/sort.h
@@ -20,8 +20,8 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/alloca.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/stable_sort.h b/cel-c/internal/stable_sort.h
index 5c3f62c..9e75f79 100644
--- a/cel-c/internal/stable_sort.h
+++ b/cel-c/internal/stable_sort.h
@@ -20,8 +20,8 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/alloca.h"
+#include "cel-c/internal/config.h"
 
 CEL_BEGIN_DECLS
 
diff --git a/cel-c/internal/string.h b/cel-c/internal/string.h
index 87c3aca..9e35360 100644
--- a/cel-c/internal/string.h
+++ b/cel-c/internal/string.h
@@ -23,8 +23,8 @@
 #include <stddef.h>
 
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
 #include "cel-c/cstring_view.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_string.h"
 #include "cel-c/string_view.h"
 
diff --git a/cel-c/internal/string_test.cc b/cel-c/internal/string_test.cc
index cb7f9e6..94449a0 100644
--- a/cel-c/internal/string_test.cc
+++ b/cel-c/internal/string_test.cc
@@ -19,8 +19,8 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "cel-c/alloc.h"
-#include "cel-c/config.h"
 #include "cel-c/cstring_view.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/generic_string.h"
 #include "cel-c/string_view.h"
 
diff --git a/cel-c/internal/struct_value.cc b/cel-c/internal/struct_value.cc
index 8807122..019f6a6 100644
--- a/cel-c/internal/struct_value.cc
+++ b/cel-c/internal/struct_value.cc
@@ -18,8 +18,8 @@
 #include <string.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/internal/array.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/sort.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
diff --git a/cel-c/internal/struct_value_test.cc b/cel-c/internal/struct_value_test.cc
index 304a1fb..4a3816c 100644
--- a/cel-c/internal/struct_value_test.cc
+++ b/cel-c/internal/struct_value_test.cc
@@ -16,9 +16,9 @@
 #include <cstdlib>
 
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/value_testing.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
diff --git a/cel-c/internal/testing/BUILD b/cel-c/internal/testing/BUILD
index ee4b012..fa9f4f3 100644
--- a/cel-c/internal/testing/BUILD
+++ b/cel-c/internal/testing/BUILD
@@ -29,10 +29,10 @@ cc_library(
         "//cel-c:assert",
         "//cel-c:ast",
         "//cel-c:ast_proto",
-        "//cel-c:config",
         "//cel-c:status",
         "//cel-c:string_view",
         "//cel-c:string_view_absl",
+        "//cel-c/internal:config",
         "@abseil-cpp//absl/log:absl_check",
         "@abseil-cpp//absl/log:die_if_null",
         "@cel-cpp//checker:checker_options",
@@ -58,8 +58,8 @@ cc_library(
         "//cel-c:arena",
         "//cel-c:assert",
         "//cel-c:ast",
-        "//cel-c:config",
         "//cel-c:string_view",
+        "//cel-c/internal:config",
     ],
 )
 
@@ -69,7 +69,7 @@ cc_library(
     hdrs = ["def_pool.h"],
     deps = [
         "//cel-c:assert",
-        "//cel-c:config",
+        "//cel-c/internal:config",
         "@abseil-cpp//absl/log:die_if_null",
         "@cel-spec//proto/cel/expr/conformance/proto3:test_all_types_upb_proto_reflection",
         "@protobuf//:any_upb_reflection_proto",
@@ -92,10 +92,10 @@ cc_library(
         "//cel-c:assert",
         "//cel-c:ast",
         "//cel-c:ast_proto",
-        "//cel-c:config",
         "//cel-c:status",
         "//cel-c:string_view",
         "//cel-c:string_view_absl",
+        "//cel-c/internal:config",
         "@abseil-cpp//absl/log:absl_check",
         "@abseil-cpp//absl/log:die_if_null",
         "@cel-cpp//common:ast_proto",
@@ -121,7 +121,7 @@ cc_library(
         "//cel-c:arena",
         "//cel-c:assert",
         "//cel-c:ast",
-        "//cel-c:config",
         "//cel-c:string_view",
+        "//cel-c/internal:config",
     ],
 )
diff --git a/cel-c/internal/testing/compile.cc b/cel-c/internal/testing/compile.cc
index 1c230c6..df6efe9 100644
--- a/cel-c/internal/testing/compile.cc
+++ b/cel-c/internal/testing/compile.cc
@@ -17,7 +17,7 @@
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/testing/compiler.h"
 #include "cel-c/string_view.h"
 
diff --git a/cel-c/internal/testing/compile.h b/cel-c/internal/testing/compile.h
index 3a128a7..24e1e67 100644
--- a/cel-c/internal/testing/compile.h
+++ b/cel-c/internal/testing/compile.h
@@ -17,7 +17,7 @@
 
 #include "cel-c/arena.h"
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/testing/compiler.cc b/cel-c/internal/testing/compiler.cc
index 36c5937..8d1867d 100644
--- a/cel-c/internal/testing/compiler.cc
+++ b/cel-c/internal/testing/compiler.cc
@@ -26,7 +26,7 @@
 #include "cel-c/assert.h"
 #include "cel-c/ast.h"
 #include "cel-c/ast_proto.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
 #include "cel-c/string_view_absl.h"
diff --git a/cel-c/internal/testing/compiler.h b/cel-c/internal/testing/compiler.h
index 9f1f7ed..8adebd2 100644
--- a/cel-c/internal/testing/compiler.h
+++ b/cel-c/internal/testing/compiler.h
@@ -17,7 +17,7 @@
 
 #include "cel-c/arena.h"
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 
 #ifdef __cplusplus
diff --git a/cel-c/internal/testing/def_pool.cc b/cel-c/internal/testing/def_pool.cc
index cc503d8..fbd0333 100644
--- a/cel-c/internal/testing/def_pool.cc
+++ b/cel-c/internal/testing/def_pool.cc
@@ -22,7 +22,7 @@
 #include "google/protobuf/wrappers.upbdefs.h"
 #include "absl/log/die_if_null.h"
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel/expr/conformance/proto3/test_all_types.upbdefs.h"
 #include "upb/reflection/def.h"
 
diff --git a/cel-c/internal/testing/def_pool.h b/cel-c/internal/testing/def_pool.h
index 9bef00a..8c05945 100644
--- a/cel-c/internal/testing/def_pool.h
+++ b/cel-c/internal/testing/def_pool.h
@@ -15,7 +15,7 @@
 #ifndef THIRD_PARTY_CEL_C_INTERNAL_TESTING_DEF_POOL_H_
 #define THIRD_PARTY_CEL_C_INTERNAL_TESTING_DEF_POOL_H_
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "upb/reflection/def.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/testing/parse.cc b/cel-c/internal/testing/parse.cc
index 799ca94..8e7cfbc 100644
--- a/cel-c/internal/testing/parse.cc
+++ b/cel-c/internal/testing/parse.cc
@@ -17,7 +17,7 @@
 #include "cel-c/arena.h"
 #include "cel-c/assert.h"
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/testing/parser.h"
 #include "cel-c/string_view.h"
 
diff --git a/cel-c/internal/testing/parse.h b/cel-c/internal/testing/parse.h
index 33779c3..0ec2fac 100644
--- a/cel-c/internal/testing/parse.h
+++ b/cel-c/internal/testing/parse.h
@@ -17,7 +17,7 @@
 
 #include "cel-c/arena.h"
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/testing/parser.cc b/cel-c/internal/testing/parser.cc
index 34e3f80..5720f1e 100644
--- a/cel-c/internal/testing/parser.cc
+++ b/cel-c/internal/testing/parser.cc
@@ -28,7 +28,7 @@
 #include "cel-c/assert.h"
 #include "cel-c/ast.h"
 #include "cel-c/ast_proto.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/string_view.h"
 #include "cel-c/string_view_absl.h"
diff --git a/cel-c/internal/testing/parser.h b/cel-c/internal/testing/parser.h
index e20f857..36453e6 100644
--- a/cel-c/internal/testing/parser.h
+++ b/cel-c/internal/testing/parser.h
@@ -17,7 +17,7 @@
 
 #include "cel-c/arena.h"
 #include "cel-c/ast.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/string_view.h"
 
 #ifdef __cplusplus
diff --git a/cel-c/internal/trilean_test.cc b/cel-c/internal/trilean_test.cc
index 315baeb..a5b2c6b 100644
--- a/cel-c/internal/trilean_test.cc
+++ b/cel-c/internal/trilean_test.cc
@@ -16,7 +16,7 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 
 namespace {
 
diff --git a/cel-c/internal/uchar.h b/cel-c/internal/uchar.h
index ea6b9e0..ab31ec5 100644
--- a/cel-c/internal/uchar.h
+++ b/cel-c/internal/uchar.h
@@ -20,7 +20,7 @@
 
 #include <stdint.h>  // IWYU pragma: keep
 
-#include "cel-c/config.h"  // IWYU pragma: keep
+#include "cel-c/internal/config.h"  // IWYU pragma: keep
 
 #if !defined(__cplusplus) || __cplusplus < 201103L
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/unicode.h b/cel-c/internal/unicode.h
index fe4b0b1..d7c961f 100644
--- a/cel-c/internal/unicode.h
+++ b/cel-c/internal/unicode.h
@@ -20,7 +20,7 @@
 #include <stdbool.h>  // IWYU pragma: keep
 #include <stdint.h>
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/uchar.h"  // IWYU pragma: keep
 
 CEL_BEGIN_DECLS
diff --git a/cel-c/internal/utf8.cc b/cel-c/internal/utf8.cc
index 587bb15..74b093e 100644
--- a/cel-c/internal/utf8.cc
+++ b/cel-c/internal/utf8.cc
@@ -19,7 +19,7 @@
 #include <stdint.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/uchar.h"  // IWYU pragma: keep
 #include "cel-c/internal/unicode.h"
 #include "upb/base/string_view.h"
diff --git a/cel-c/internal/utf8.h b/cel-c/internal/utf8.h
index d2a7a04..6a99fa9 100644
--- a/cel-c/internal/utf8.h
+++ b/cel-c/internal/utf8.h
@@ -21,7 +21,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/uchar.h"  // IWYU pragma: keep
 #include "upb/base/string_view.h"
 
diff --git a/cel-c/internal/value.cc b/cel-c/internal/value.cc
index e538da8..31efab0 100644
--- a/cel-c/internal/value.cc
+++ b/cel-c/internal/value.cc
@@ -19,11 +19,11 @@
 #include <stdlib.h>
 
 #include "cel-c/assert.h"
-#include "cel-c/config.h"
 #include "cel-c/duration.h"
 #include "cel-c/error.h"
 #include "cel-c/error_code.h"
 #include "cel-c/internal/any.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/parsed_map_field_value.h"
 #include "cel-c/internal/parsed_message_value.h"
 #include "cel-c/internal/parsed_repeated_field_value.h"
diff --git a/cel-c/internal/value_test.cc b/cel-c/internal/value_test.cc
index d3df729..c2e87f3 100644
--- a/cel-c/internal/value_test.cc
+++ b/cel-c/internal/value_test.cc
@@ -17,9 +17,9 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "absl/strings/string_view.h"
-#include "cel-c/config.h"
 #include "cel-c/duration.h"
 #include "cel-c/error.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/internal/empty_list_value.h"
 #include "cel-c/internal/empty_map_value.h"
 #include "cel-c/internal/mutable_list_value.h"
diff --git a/cel-c/internal/value_testing.cc b/cel-c/internal/value_testing.cc
index 1b93d64..ee721b5 100644
--- a/cel-c/internal/value_testing.cc
+++ b/cel-c/internal/value_testing.cc
@@ -34,7 +34,7 @@
 #include "absl/log/die_if_null.h"
 #include "absl/strings/string_view.h"
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/value.h"
 #include "cel-c/well_known_types.h"
diff --git a/cel-c/internal/value_testing.h b/cel-c/internal/value_testing.h
index fc39f2b..4fd891b 100644
--- a/cel-c/internal/value_testing.h
+++ b/cel-c/internal/value_testing.h
@@ -20,7 +20,7 @@
 #include "absl/strings/string_view.h"
 #include "cel-c/alloc.h"
 #include "cel-c/arena.h"
-#include "cel-c/config.h"
+#include "cel-c/internal/config.h"
 #include "cel-c/status.h"
 #include "cel-c/value.h"
 #include "cel-c/well_known_types.h"