diff --git a/lisp/llvm-lib/llvm-act-on-file/make-tmp-output-file.el b/lisp/llvm-lib/llvm-act-on-file/make-tmp-output-file.el
index a721ce3..cfb1407 100644
--- a/lisp/llvm-lib/llvm-act-on-file/make-tmp-output-file.el
+++ b/lisp/llvm-lib/llvm-act-on-file/make-tmp-output-file.el
@@ -36,7 +36,7 @@
       (setq fname (file-name-nondirectory (file-name-sans-extension file))
             temporary-file-directory (expand-file-name "tmp" file-directory)))
 
-    (when (not (file-exists-p temporary-file-directory))
+    (unless (file-exists-p temporary-file-directory)
       (make-directory temporary-file-directory))
     (make-temp-file (concat fname "-")
                     nil ext)))