diff --git a/Library/Homebrew/unpack_strategy.rb b/Library/Homebrew/unpack_strategy.rb
index 26bc872286..2f578b3514 100644
--- a/Library/Homebrew/unpack_strategy.rb
+++ b/Library/Homebrew/unpack_strategy.rb
@@ -136,6 +136,8 @@ module UnpackStrategy
       end
 
       Directory.new(tmp_unpack_dir).extract(to: to, verbose: verbose)
+
+      FileUtils.chmod_R "+w", tmp_unpack_dir
     end
   end