diff --git a/gc/default/default.c b/gc/default/default.c
index b69fbeb1d9..be0be4a373 100644
--- a/gc/default/default.c
+++ b/gc/default/default.c
@@ -6094,8 +6094,8 @@ rb_gc_impl_writebarrier(void *objspace_ptr, VALUE a, VALUE b)
     if (SPECIAL_CONST_P(a)) rb_bug("rb_gc_writebarrier: a is special const: %"PRIxVALUE, a);
     if (SPECIAL_CONST_P(b)) rb_bug("rb_gc_writebarrier: b is special const: %"PRIxVALUE, b);
 #else
-    ASSUME(!SPECIAL_CONST_P(a));
-    ASSUME(!SPECIAL_CONST_P(b));
+    RBIMPL_ASSERT_OR_ASSUME(!SPECIAL_CONST_P(a));
+    RBIMPL_ASSERT_OR_ASSUME(!SPECIAL_CONST_P(b));
 #endif
 
     GC_ASSERT(!during_gc);