diff --git a/Library/Homebrew/build_environment.rb b/Library/Homebrew/build_environment.rb
index 10fecf1579..48eac54ff6 100644
--- a/Library/Homebrew/build_environment.rb
+++ b/Library/Homebrew/build_environment.rb
@@ -49,6 +49,7 @@ class BuildEnvironment
     CMAKE_PREFIX_PATH CMAKE_INCLUDE_PATH CMAKE_LIBRARY_PATH CMAKE_FRAMEWORK_PATH
     MACOSX_DEPLOYMENT_TARGET PKG_CONFIG_PATH PKG_CONFIG_LIBDIR
     HOMEBREW_DEBUG HOMEBREW_MAKE_JOBS HOMEBREW_VERBOSE
+    all_proxy ftp_proxy http_proxy https_proxy no_proxy
     HOMEBREW_SVN HOMEBREW_GIT
     HOMEBREW_SDKROOT
     MAKE GIT CPP