diff --git a/ChangeLog b/ChangeLog
index 98976d4d10..8cc623d8c9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed Feb  5 11:46:42 2014  Koichi Sasada  <ko1@atdot.net>
+
+	* gc.c (gc_mark_children): STR_ASSOC is no longer available.
+	  Reported by @nagachika.
+	  http://d.hatena.ne.jp/nagachika/20140204
+
 Wed Feb  5 11:27:22 2014  Koichi Sasada  <ko1@atdot.net>
 
 	* string.c (rb_str_new_frozen): refactoring code.
diff --git a/gc.c b/gc.c
index 8bafb724a1..db32c3705e 100644
--- a/gc.c
+++ b/gc.c
@@ -3866,8 +3866,7 @@ gc_mark_children(rb_objspace_t *objspace, VALUE ptr)
 	goto again;
 
       case T_STRING:
-#define STR_ASSOC FL_USER3   /* copied from string.c */
-	if (FL_TEST(obj, RSTRING_NOEMBED) && FL_ANY(obj, ELTS_SHARED|STR_ASSOC)) {
+	if (STR_SHARED_P(obj)) {
 	    ptr = obj->as.string.as.heap.aux.shared;
 	    goto again;
 	}