diff --git a/Library/Homebrew/extend/pathname.rb b/Library/Homebrew/extend/pathname.rb
index d44f59968b..20da2cc739 100644
--- a/Library/Homebrew/extend/pathname.rb
+++ b/Library/Homebrew/extend/pathname.rb
@@ -245,9 +245,10 @@ class Pathname
   end
 
   def ensure_writable
-    saved_perms = unless writable?
+    saved_perms = nil
+    unless writable?
+      saved_perms = stat.mode
       chmod 0644
-      stat.mode
     end
     yield
   ensure