diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index 72380372e8..0af37578dc 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -28,6 +28,11 @@ module OS
       version >= "10.12"
     end
 
+    def outdated_release?
+      # TODO: bump version when new OS is released
+      version < "10.9"
+    end
+
     def cat
       version.to_sym
     end