diff --git a/Library/Homebrew/cask/test/cask/dsl_test.rb b/Library/Homebrew/cask/test/cask/dsl_test.rb
index 96095ed70b..1e13d49f32 100644
--- a/Library/Homebrew/cask/test/cask/dsl_test.rb
+++ b/Library/Homebrew/cask/test/cask/dsl_test.rb
@@ -123,10 +123,6 @@ describe Hbc::DSL do
   end
 
   describe "language stanza" do
-    after(:each) do
-      ENV["HOMEBREW_LANGUAGES"] = nil
-    end
-
     it "allows multilingual casks" do
       cask = lambda {
         Hbc::Cask.new("cask-with-apps") do
@@ -144,13 +140,13 @@ describe Hbc::DSL do
         end
       }
 
-      ENV["HOMEBREW_LANGUAGES"] = "FIRST_LANGUAGE"
+      MacOS.stubs(languages: ["FIRST_LANGUAGE"])
       cask.call.language.must_equal :first
 
-      ENV["HOMEBREW_LANGUAGES"] = "SECOND_LANGUAGE"
+      MacOS.stubs(languages: ["SECOND_LANGUAGE"])
       cask.call.language.must_equal :second
 
-      ENV["HOMEBREW_LANGUAGES"] = "THIRD_LANGUAGE"
+      MacOS.stubs(languages: ["THIRD_LANGUAGE"])
       cask.call.language.must_equal :default
     end
   end
diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index 854d39174c..1b207a538b 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -42,10 +42,10 @@ module OS
     end
 
     def languages
-      if ENV["HOMEBREW_LANGUAGES"]
+      @languages ||= if ENV["HOMEBREW_LANGUAGES"]
         ENV["HOMEBREW_LANGUAGES"].split(",")
       else
-        @languages ||= Utils.popen_read("defaults", "read", ".GlobalPreferences", "AppleLanguages").scan(/[^ \n"(),]+/)
+        Utils.popen_read("defaults", "read", ".GlobalPreferences", "AppleLanguages").scan(/[^ \n"(),]+/)
       end
     end