diff --git a/Library/Homebrew/cmd/audit.rb b/Library/Homebrew/cmd/audit.rb
index 6812dd1182..b61d58817a 100644
--- a/Library/Homebrew/cmd/audit.rb
+++ b/Library/Homebrew/cmd/audit.rb
@@ -385,6 +385,10 @@ class FormulaAuditor
     if text =~ /def options/
       problem "Use new-style option definitions."
     end
+
+    if text =~ /MACOS_VERSION/
+      problem "Use MacOS.version instead of MACOS_VERSION"
+    end
   end
 
   def audit