diff --git a/ChangeLog b/ChangeLog
index dcdf6b8b7f..4230660260 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -45,6 +45,11 @@ Wed Jan  7 08:21:04 2004  Dave Thomas  <dave@pragprog.com>
 	  line in files that would otherwise be treated as
 	  plain text.
 
+Tue Jan  6 22:13:34 2004  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* eval.c (rb_mod_modfunc): should break if m has no super class.
+	  [ruby-dev:22498]
+
 Tue Jan  6 21:51:37 2004  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* io.c (fptr_finalize): should save errno just after failure.
diff --git a/eval.c b/eval.c
index e764e5c23e..d3de7f4db9 100644
--- a/eval.c
+++ b/eval.c
@@ -7055,6 +7055,7 @@ rb_mod_modfunc(argc, argv, module)
 		break;		/* normal case: need not to follow 'super' link */
 	    }
 	    m = RCLASS(m)->super;
+	    if (!m) break;
 	}
 	rb_add_method(rb_singleton_class(module), id, body->nd_body, NOEX_PUBLIC);
     }