diff --git a/gc/gc.h b/gc/gc.h
index d147a31..2a20d65 100644
--- a/gc/gc.h
+++ b/gc/gc.h
@@ -110,7 +110,7 @@ MODULAR_GC_FN void rb_gc_mark_roots(void *objspace, const char **categoryp);
 MODULAR_GC_FN void rb_gc_ractor_newobj_cache_foreach(void (*func)(void *cache, void *data), void *data);
 MODULAR_GC_FN bool rb_gc_multi_ractor_p(void);
 MODULAR_GC_FN bool rb_gc_shutdown_call_finalizer_p(VALUE obj);
-MODULAR_GC_FN void rb_gc_obj_changed_pool(VALUE obj, size_t heap_id);
+MODULAR_GC_FN void rb_gc_obj_changed_slot_size(VALUE obj, size_t slot_size);
 MODULAR_GC_FN void rb_gc_prepare_heap_process_object(VALUE obj);
 MODULAR_GC_FN bool rb_memerror_reentered(void);
 MODULAR_GC_FN bool rb_obj_id_p(VALUE);
diff --git a/gc/gc_impl.h b/gc/gc_impl.h
index b8417fd..892831c 100644
--- a/gc/gc_impl.h
+++ b/gc/gc_impl.h
@@ -38,7 +38,6 @@ GC_IMPL_FN void rb_gc_impl_objspace_init(void *objspace_ptr);
 GC_IMPL_FN void *rb_gc_impl_ractor_cache_alloc(void *objspace_ptr, void *ractor);
 GC_IMPL_FN void rb_gc_impl_set_params(void *objspace_ptr);
 GC_IMPL_FN void rb_gc_impl_init(void);
-GC_IMPL_FN size_t *rb_gc_impl_heap_sizes(void *objspace_ptr);
 // Shutdown
 GC_IMPL_FN void rb_gc_impl_shutdown_free_objects(void *objspace_ptr);
 GC_IMPL_FN void rb_gc_impl_objspace_free(void *objspace_ptr);
@@ -56,9 +55,9 @@ GC_IMPL_FN VALUE rb_gc_impl_config_get(void *objspace_ptr);
 GC_IMPL_FN void rb_gc_impl_config_set(void *objspace_ptr, VALUE hash);
 GC_IMPL_FN struct rb_gc_vm_context *rb_gc_impl_get_vm_context(void *objspace_ptr);
 // Object allocation
-GC_IMPL_FN VALUE rb_gc_impl_new_obj(void *objspace_ptr, void *cache_ptr, VALUE klass, VALUE flags, bool wb_protected, size_t alloc_size);
+GC_IMPL_FN VALUE rb_gc_impl_new_obj(void *objspace_ptr, void *cache_ptr, VALUE klass, VALUE flags, bool wb_protected, size_t alloc_size, size_t *actual_alloc_size);
 GC_IMPL_FN size_t rb_gc_impl_obj_slot_size(VALUE obj);
-GC_IMPL_FN size_t rb_gc_impl_heap_id_for_size(void *objspace_ptr, size_t size);
+GC_IMPL_FN size_t rb_gc_impl_size_slot_size(void *objspace_ptr, size_t size);
 GC_IMPL_FN bool rb_gc_impl_size_allocatable_p(size_t size);
 // Malloc
 /*
diff --git a/gc/mmtk/mmtk.c b/gc/mmtk/mmtk.c
index d996b92..3600a3d 100644
--- a/gc/mmtk/mmtk.c
+++ b/gc/mmtk/mmtk.c
@@ -687,12 +687,6 @@ rb_gc_impl_init(void)
     rb_define_singleton_method(rb_mGC, "verify_compaction_references", rb_f_notimplement, -1);
 }
 
-size_t *
-rb_gc_impl_heap_sizes(void *objspace_ptr)
-{
-    return heap_sizes;
-}
-
 int
 rb_mmtk_obj_free_iter_wrapper(VALUE obj, void *data)
 {
@@ -902,7 +896,7 @@ mmtk_post_alloc_fast_immix(struct objspace *objspace, struct MMTk_ractor_cache *
 }
 
 VALUE
-rb_gc_impl_new_obj(void *objspace_ptr, void *cache_ptr, VALUE klass, VALUE flags, bool wb_protected, size_t alloc_size)
+rb_gc_impl_new_obj(void *objspace_ptr, void *cache_ptr, VALUE klass, VALUE flags, bool wb_protected, size_t alloc_size, size_t *actual_alloc_size)
 {
 #define MMTK_ALLOCATION_SEMANTICS_DEFAULT 0
     struct objspace *objspace = objspace_ptr;
@@ -916,6 +910,7 @@ rb_gc_impl_new_obj(void *objspace_ptr, void *cache_ptr, VALUE klass, VALUE flags
             break;
         }
     }
+    *actual_alloc_size = alloc_size;
 
     if (objspace->gc_stress) {
         mmtk_handle_user_collection_request(ractor_cache, false, false);
@@ -962,10 +957,10 @@ rb_gc_impl_obj_slot_size(VALUE obj)
 }
 
 size_t
-rb_gc_impl_heap_id_for_size(void *objspace_ptr, size_t size)
+rb_gc_impl_size_slot_size(void *objspace_ptr, size_t size)
 {
     for (int i = 0; i < MMTK_HEAP_COUNT; i++) {
-        if (size <= heap_sizes[i]) return i;
+        if (size <= heap_sizes[i]) return heap_sizes[i];
     }
 
     rb_bug("size too big");
diff --git a/test/.excludes-mmtk/TestGc.rb b/test/.excludes-mmtk/TestGc.rb
index cbab458..4413f03 100644
--- a/test/.excludes-mmtk/TestGc.rb
+++ b/test/.excludes-mmtk/TestGc.rb
@@ -15,6 +15,10 @@
 exclude(:test_old_to_young_reference, "testing behaviour specific to default GC")
 exclude(:test_profiler_enabled, "MMTk does not have GC::Profiler")
 exclude(:test_profiler_raw_data, "MMTk does not have GC::Profiler")
+exclude(:test_profiler_raw_data_since, "MMTk does not have GC::Profiler")
+exclude(:test_profiler_raw_data_limit, "MMTk does not have GC::Profiler")
+exclude(:test_profiler_raw_data_reports_compaction_separately_from_sweep_wall_time, "MMTk does not have GC::Profiler")
+exclude(:test_profiler_raw_data_includes_wall_time, "MMTk does not have GC::Profiler")
 exclude(:test_profiler_total_time, "MMTk does not have GC::Profiler")
 exclude(:test_start_full_mark, "testing behaviour specific to default GC")
 exclude(:test_start_immediate_sweep, "testing behaviour specific to default GC")