diff --git a/.github/workflows/compilers.yml b/.github/workflows/compilers.yml
index 3df3153ff7..0c6d2bf699 100644
--- a/.github/workflows/compilers.yml
+++ b/.github/workflows/compilers.yml
@@ -181,7 +181,7 @@ jobs:
 #         - { name: DEBUG_INTEGER_PACK,             env: { cppflags: '-DDEBUG_INTEGER_PACK' } }
 #         - { name: ENABLE_PATH_CHECK,              env: { cppflags: '-DENABLE_PATH_CHECK' } }
 
-          - { name: GC_DEBUG_STRESS_TO_CLASS,       env: { cppflags: '-DGC_DEBUG_STRESS_TO_CLASS' } }
+#         - { name: GC_DEBUG_STRESS_TO_CLASS,       env: { cppflags: '-DGC_DEBUG_STRESS_TO_CLASS' } }
 #         - { name: GC_ENABLE_LAZY_SWEEP=0,         env: { cppflags: '-DGC_ENABLE_LAZY_SWEEP=0' } }
 #         - { name: GC_PROFILE_DETAIL_MEMOTY,       env: { cppflags: '-DGC_PROFILE_DETAIL_MEMOTY' } }
 #         - { name: GC_PROFILE_MORE_DETAIL,         env: { cppflags: '-DGC_PROFILE_MORE_DETAIL' } }
diff --git a/gc.c b/gc.c
index 6db908dbbb..976f72a1ea 100644
--- a/gc.c
+++ b/gc.c
@@ -492,7 +492,7 @@ int ruby_rgengc_debug;
 #endif
 
 #ifndef GC_DEBUG_STRESS_TO_CLASS
-#define GC_DEBUG_STRESS_TO_CLASS 0
+#define GC_DEBUG_STRESS_TO_CLASS RUBY_DEBUG
 #endif
 
 #ifndef RGENGC_OBJ_INFO
@@ -1044,8 +1044,10 @@ VALUE *ruby_initial_gc_stress_ptr = &ruby_initial_gc_stress;
 #define ruby_gc_stress_mode     objspace->gc_stress_mode
 #if GC_DEBUG_STRESS_TO_CLASS
 #define stress_to_class         objspace->stress_to_class
+#define set_stress_to_class(c)  (stress_to_class = (c))
 #else
-#define stress_to_class         0
+#define stress_to_class         (objspace, 0)
+#define set_stress_to_class(c)  (objspace, (c))
 #endif
 
 #if 0
@@ -2845,14 +2847,12 @@ newobj_of0(VALUE klass, VALUE flags, int wb_protected, rb_ractor_t *cr, size_t a
     RB_DEBUG_COUNTER_INC(obj_newobj);
     (void)RB_DEBUG_COUNTER_INC_IF(obj_newobj_wb_unprotected, !wb_protected);
 
-#if GC_DEBUG_STRESS_TO_CLASS
     if (UNLIKELY(stress_to_class)) {
         long i, cnt = RARRAY_LEN(stress_to_class);
         for (i = 0; i < cnt; ++i) {
             if (klass == RARRAY_AREF(stress_to_class, i)) rb_memerror();
         }
     }
-#endif
 
     size_t size_pool_idx = size_pool_idx_for_size(alloc_size);
 
@@ -13805,7 +13805,6 @@ rb_gcdebug_sentinel(VALUE obj, const char *name)
 
 #endif /* GC_DEBUG */
 
-#if GC_DEBUG_STRESS_TO_CLASS
 /*
  *  call-seq:
  *    GC.add_stress_to_class(class[, ...])
@@ -13819,7 +13818,7 @@ rb_gcdebug_add_stress_to_class(int argc, VALUE *argv, VALUE self)
     rb_objspace_t *objspace = &rb_objspace;
 
     if (!stress_to_class) {
-        stress_to_class = rb_ary_hidden_new(argc);
+        set_stress_to_class(rb_ary_hidden_new(argc));
     }
     rb_ary_cat(stress_to_class, argv, argc);
     return self;
@@ -13844,12 +13843,11 @@ rb_gcdebug_remove_stress_to_class(int argc, VALUE *argv, VALUE self)
             rb_ary_delete_same(stress_to_class, argv[i]);
         }
         if (RARRAY_LEN(stress_to_class) == 0) {
-            stress_to_class = 0;
+            set_stress_to_class(0);
         }
     }
     return Qnil;
 }
-#endif
 
 /*
  * Document-module: ObjectSpace
@@ -13975,10 +13973,10 @@ Init_GC(void)
         rb_define_singleton_method(rb_mGC, "verify_compaction_references", rb_f_notimplement, -1);
     }
 
-#if GC_DEBUG_STRESS_TO_CLASS
-    rb_define_singleton_method(rb_mGC, "add_stress_to_class", rb_gcdebug_add_stress_to_class, -1);
-    rb_define_singleton_method(rb_mGC, "remove_stress_to_class", rb_gcdebug_remove_stress_to_class, -1);
-#endif
+    if (GC_DEBUG_STRESS_TO_CLASS) {
+        rb_define_singleton_method(rb_mGC, "add_stress_to_class", rb_gcdebug_add_stress_to_class, -1);
+        rb_define_singleton_method(rb_mGC, "remove_stress_to_class", rb_gcdebug_remove_stress_to_class, -1);
+    }
 
     {
         VALUE opts;