diff --git a/lisp/vc/ediff.el b/lisp/vc/ediff.el
index 3a2d1e4..e5c12cc 100644
--- a/lisp/vc/ediff.el
+++ b/lisp/vc/ediff.el
@@ -1367,7 +1367,8 @@ ediff-patch-file
     (require 'ediff-ptch)
     (setq patch-buf
 	  (ediff-get-patch-buffer
-	   (if arg (prefix-numeric-value arg)) patch-buf))
+	   (if arg (prefix-numeric-value arg)) (and (stringp patch-buf)
+                                                    (get-buffer patch-buf))))
     (setq source-dir (cond (ediff-use-last-dir ediff-last-dir-patch)
 			   ((and (not ediff-patch-default-directory)
 				 (buffer-file-name patch-buf))