diff --git a/Library/Homebrew/default_prefix.rb b/Library/Homebrew/default_prefix.rb
index 49917cdd16..81c85ebcaa 100644
--- a/Library/Homebrew/default_prefix.rb
+++ b/Library/Homebrew/default_prefix.rb
@@ -5,3 +5,5 @@ module Homebrew
   DEFAULT_PREFIX = HOMEBREW_DEFAULT_PREFIX
   DEFAULT_REPOSITORY = HOMEBREW_DEFAULT_REPOSITORY
 end
+
+require "extend/os/default_prefix"