diff --git a/ChangeLog b/ChangeLog
index d0c5398215..87c6ffc2ab 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat May 25 11:27:32 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vm_method.c (set_method_visibility): quote unprintable method name.
+
 Sat May 25 11:24:24 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* eval.c (rb_frame_callee): returns the called name of the current
diff --git a/vm_method.c b/vm_method.c
index 3882b98d4e..c9f04942e1 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -1274,7 +1274,8 @@ set_method_visibility(VALUE self, int argc, VALUE *argv, rb_method_flag_t ex)
     secure_visibility(self);
 
     if (argc == 0) {
-	rb_warning("%s with no argument is just ignored", rb_id2name(rb_frame_callee()));
+	rb_warning("%"PRIsVALUE" with no argument is just ignored",
+		   QUOTE_ID(rb_frame_callee()));
     }
 
     for (i = 0; i < argc; i++) {