diff --git a/Library/Homebrew/os/mac/xquartz.rb b/Library/Homebrew/os/mac/xquartz.rb
index c906da38e4..e46d8da271 100644
--- a/Library/Homebrew/os/mac/xquartz.rb
+++ b/Library/Homebrew/os/mac/xquartz.rb
@@ -122,7 +122,7 @@ module OS
       private
 
       def use_sdk?
-        not (prefix.to_s == '/opt/X11' or MacOS::CLT.installed?)
+        provided_by_apple? && Xcode.without_clt?
       end
     end
   end