diff --git a/ChangeLog b/ChangeLog
index 4d09768a66..3ffc06ebea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Jun 19 07:06:21 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* gc.c (rgengc_remember): check T_NONE and T_ZOMBIE
+	  if RGENGC_CHECK_MODE > 0.
+
 Wed Jun 19 07:02:19 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* gc.c (RGENGC_CHECK_MODE): add new check mode `3'.
diff --git a/gc.c b/gc.c
index 55eb33440b..2b26037704 100644
--- a/gc.c
+++ b/gc.c
@@ -3632,6 +3632,19 @@ rgengc_remember(rb_objspace_t *objspace, VALUE obj)
 		  RVALUE_SHADY(obj) ? "shady" : "non-shady",
 		  rgengc_remembersetbits_get(objspace, obj) ? "was already remembered" : "is remembered now");
 
+#if RGENGC_CHECK_MODE > 0
+    {
+	switch (BUILTIN_TYPE(obj)) {
+	  case T_NONE:
+	  case T_ZOMBIE:
+	    rb_bug("rgengc_remember: should not remember %p (%s)\n",
+		   (void *)obj, obj_type_name(obj));
+	  default:
+	    ;
+	}
+    }
+#endif
+
     if (RGENGC_PROFILE) {
 	if (!rgengc_remembered(objspace, obj)) {
 	    if (!RVALUE_SHADY(obj)) {