diff --git a/Library/Homebrew/cmd/config.rb b/Library/Homebrew/cmd/config.rb
index 0e91845c68..037294655d 100644
--- a/Library/Homebrew/cmd/config.rb
+++ b/Library/Homebrew/cmd/config.rb
@@ -91,7 +91,7 @@ module Homebrew
   end
 
   # we try to keep output minimal
-  def dump_build_config(f)
+  def dump_build_config(f=STDOUT)
     f.puts "HOMEBREW_VERSION: #{HOMEBREW_VERSION}"
     f.puts "HEAD: #{head}"
     f.puts "HOMEBREW_PREFIX: #{HOMEBREW_PREFIX}" if HOMEBREW_PREFIX.to_s != "/usr/local"