diff --git a/source/numerics.tex b/source/numerics.tex
index f228a4ed5c..aa3f70b8ca 100644
--- a/source/numerics.tex
+++ b/source/numerics.tex
@@ -9210,8 +9210,8 @@
 #define @\libmacro{HUGE_VAL}@ @\seebelow@
 #define @\libmacro{HUGE_VALF}@ @\seebelow@
 #define @\libmacro{HUGE_VALL}@ @\seebelow@
-#define @\libmacro{INFINITY}@ @\seebelow@
-#define @\libmacro{NAN}@ @\seebelow@
+#define @\libmacro{INFINITY}@ @\seebelow@      // optional
+#define @\libmacro{NAN}@ @\seebelow@           // optional
 #define @\libmacro{FP_INFINITE}@ @\seebelow@
 #define @\libmacro{FP_NAN}@ @\seebelow@
 #define @\libmacro{FP_NORMAL}@ @\seebelow@
diff --git a/source/support.tex b/source/support.tex
index 9eeaba1426..1b063faa4b 100644
--- a/source/support.tex
+++ b/source/support.tex
@@ -1830,11 +1830,11 @@
 #define @\libmacro{FLT_ROUNDS}@ @\seebelow@
 #define @\libmacro{FLT_EVAL_METHOD}@ @\seebelow@
 #define @\libmacro{FLT_RADIX}@ @\seebelow@
-#define @\libmacro{INFINITY}@ @\seebelow@
-#define @\libmacro{NAN}@ @\seebelow@
-#define @\libmacro{FLT_SNAN}@ @\seebelow@
-#define @\libmacro{DBL_SNAN}@ @\seebelow@
-#define @\libmacro{LDBL_SNAN}@ @\seebelow@
+#define @\libmacro{INFINITY}@ @\seebelow@          // optional
+#define @\libmacro{NAN}@ @\seebelow@               // optional
+#define @\libmacro{FLT_SNAN}@ @\seebelow@          // optional
+#define @\libmacro{DBL_SNAN}@ @\seebelow@          // optional
+#define @\libmacro{LDBL_SNAN}@ @\seebelow@         // optional
 #define @\libmacro{FLT_MANT_DIG}@ @\seebelow@
 #define @\libmacro{DBL_MANT_DIG}@ @\seebelow@
 #define @\libmacro{LDBL_MANT_DIG}@ @\seebelow@