diff --git a/Library/ENV/4.3/cc b/Library/ENV/4.3/cc
index e8e586da4c..44895d28ea 100755
--- a/Library/ENV/4.3/cc
+++ b/Library/ENV/4.3/cc
@@ -242,6 +242,8 @@ class Cmd
 end
 
 if __FILE__ == $PROGRAM_NAME
+  STDOUT.sync = STDERR.sync = true
+
   ##################################################################### sanity
   abort "The build-tool has reset ENV. --env=std required." unless ENV['HOMEBREW_BREW_FILE']