diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index a4fa0a3e64e..8426b30789e 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2008-08-13  Glenn Morris  <rgm@gnu.org>
+
+	* eshell/esh-cmd.el (eshell/which): Handle the case where no description
+	is found.
+
 2008-08-12  Alan Mackenzie  <acm@muc.de>
 
 	* progmodes/cc-defs.el (c-emacs-features):
diff --git a/lisp/eshell/esh-cmd.el b/lisp/eshell/esh-cmd.el
index 82619d60791..17ae50d1f50 100644
--- a/lisp/eshell/esh-cmd.el
+++ b/lisp/eshell/esh-cmd.el
@@ -1252,9 +1252,12 @@ be finished later after the completion of an asynchronous subprocess."
 			      (prog1
 				  (describe-function sym)
 				(message nil))))))
-		(setq desc (substring desc 0
-				      (1- (or (string-match "\n" desc)
-					      (length desc)))))
+		(setq desc (if desc (substring desc 0
+					       (1- (or (string-match "\n" desc)
+						       (length desc))))
+			     ;; This should not happen.
+			     (format "%s is defined, \
+but no documentation was found" name)))
 		(if (buffer-live-p (get-buffer "*Help*"))
 		    (kill-buffer "*Help*"))
 		(setq program (or desc name))))))