diff --git a/ChangeLog b/ChangeLog
index 83d876b020..63ac6b9c31 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Oct 12 05:51:11 2009  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* regparse.c (fetch_token): warn invalid back reference
+	  and subexp call. (\k and \g).
+
 Mon Oct 12 03:47:42 2009  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* marshal.c (has_encoding): added for check the regexp
diff --git a/regparse.c b/regparse.c
index 0cc9a62e34..9f46b15cd4 100644
--- a/regparse.c
+++ b/regparse.c
@@ -3585,8 +3585,10 @@ fetch_token(OnigToken* tok, UChar** src, UChar* end, ScanEnv* env)
 	    }
 	  }
 	}
-	else
-	  PUNFETCH;
+	else {
+	    PUNFETCH;
+	    onig_syntax_warn(env, "invalid back reference");
+	}
       }
       break;
 #endif
@@ -3608,8 +3610,10 @@ fetch_token(OnigToken* tok, UChar** src, UChar* end, ScanEnv* env)
 	  tok->u.call.name_end = name_end;
 	  tok->u.call.gnum     = gnum;
 	}
-	else
-	  PUNFETCH;
+	else {
+	    onig_syntax_warn(env, "invalid subexp call");
+	    PUNFETCH;
+	}
       }
       break;
 #endif