diff --git a/gc.c b/gc.c
index 05d75e16e2..9b453cb6ed 100644
--- a/gc.c
+++ b/gc.c
@@ -2373,6 +2373,13 @@ rb_imemo_new_debug(enum imemo_type type, VALUE v1, VALUE v2, VALUE v3, VALUE v0,
 }
 #endif
 
+VALUE
+rb_class_allocate_instance(VALUE klass)
+{
+    VALUE flags = T_OBJECT | ROBJECT_EMBED;
+    return newobj_of(klass, flags, Qundef, Qundef, Qundef, RGENGC_WB_PROTECTED_OBJECT);
+}
+
 VALUE
 rb_data_object_wrap(VALUE klass, void *datap, RUBY_DATA_FUNC dmark, RUBY_DATA_FUNC dfree)
 {
diff --git a/internal/gc.h b/internal/gc.h
index 7258fed915..490f42e06a 100644
--- a/internal/gc.h
+++ b/internal/gc.h
@@ -78,6 +78,7 @@ RUBY_ATTR_MALLOC void *rb_xcalloc_mul_add_mul(size_t, size_t, size_t, size_t);
 static inline void *ruby_sized_xrealloc_inlined(void *ptr, size_t new_size, size_t old_size) RUBY_ATTR_RETURNS_NONNULL RUBY_ATTR_ALLOC_SIZE((2));
 static inline void *ruby_sized_xrealloc2_inlined(void *ptr, size_t new_count, size_t elemsiz, size_t old_count) RUBY_ATTR_RETURNS_NONNULL RUBY_ATTR_ALLOC_SIZE((2, 3));
 static inline void ruby_sized_xfree_inlined(void *ptr, size_t size);
+VALUE rb_class_allocate_instance(VALUE klass);
 
 RUBY_SYMBOL_EXPORT_BEGIN
 /* gc.c (export) */
diff --git a/object.c b/object.c
index 08fec850d3..a7fb9dd3a0 100644
--- a/object.c
+++ b/object.c
@@ -2102,13 +2102,6 @@ rb_obj_alloc(VALUE klass)
     return rb_class_alloc(klass);
 }
 
-static VALUE
-rb_class_allocate_instance(VALUE klass)
-{
-    NEWOBJ_OF(obj, struct RObject, klass, T_OBJECT | (RGENGC_WB_PROTECTED_OBJECT ? FL_WB_PROTECTED : 0));
-    return (VALUE)obj;
-}
-
 /*
  *  call-seq:
  *     class.new(args, ...)    ->  obj