diff --git a/lisp/ibuf-ext.el b/lisp/ibuf-ext.el
index 4443383cdf5..f5375612c34 100644
--- a/lisp/ibuf-ext.el
+++ b/lisp/ibuf-ext.el
@@ -347,14 +347,10 @@ the mode if ARG is omitted or nil."
    :modifier-p nil)
   (shell-command (concat command " "
 			 (shell-quote-argument
-			  (or buffer-file-name
-			      (let ((file
-				     (make-temp-file
-				      (substring
-				       (buffer-name) 0
-				       (min 10 (length (buffer-name)))))))
-				(write-region nil nil file nil 0)
-				file))))))
+			  (if buffer-file-name
+			      buffer-file-name
+			    (make-temp-file
+			     (substring (buffer-name) 0 (min 10 (length (buffer-name))))))))))
 
 ;;;###autoload (autoload 'ibuffer-do-eval "ibuf-ext")
 (define-ibuffer-op eval (form)