diff --git a/ChangeLog b/ChangeLog
index 6dcf96f7ba..d1d0edc7bf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue May 14 03:33:17 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* string.c (rb_str_new_frozen): remove debug print.
+
 Tue May 14 03:22:51 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* include/ruby/ruby.h: enable to generate write barrier protected
diff --git a/string.c b/string.c
index f02e83fbd7..59ed1b2dc4 100644
--- a/string.c
+++ b/string.c
@@ -721,9 +721,6 @@ rb_str_new_frozen(VALUE orig)
     klass = rb_obj_class(orig);
     if (STR_SHARED_P(orig) && (str = RSTRING(orig)->as.heap.aux.shared)) {
 	long ofs;
-	if (!OBJ_FROZEN(str)) {
-	    rb_bug("xyzzy");
-	}
 	assert(OBJ_FROZEN(str));
 	ofs = RSTRING_LEN(str) - RSTRING_LEN(orig);
 	if ((ofs > 0) || (klass != RBASIC(str)->klass) ||