From 80e0c45c3896e5552a387a2b533b5235b42094ce Mon Sep 17 00:00:00 2001
From: "Richard M. Stallman" <rms@gnu.org>
Date: Fri, 1 Dec 1995 18:19:34 +0000
Subject: [PATCH] (gud-sdb-marker-filter): start may be nil, so check it with
 numberp before using it.

---
 lisp/gud.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/gud.el b/lisp/gud.el
index 0f8776f3529..e7a43647a7e 100644
--- a/lisp/gud.el
+++ b/lisp/gud.el
@@ -454,7 +454,7 @@ available with older versions of GDB."
     ;; Otherwise clear gud-marker-acc. to avoid an
     ;; unnecessary concat when this function runs next.
     (setq gud-marker-acc 
-	  (if (= start (length gud-marker-acc))
+	  (if (and (numberp start) (= start (length gud-marker-acc)))
 	      (substring gud-marker-acc start)
 	    nil)))
   string)
-- 
2.39.2