diff --git a/Library/Homebrew/os/mac/xcode.rb b/Library/Homebrew/os/mac/xcode.rb
index 13a651115b..6b30e96bb9 100644
--- a/Library/Homebrew/os/mac/xcode.rb
+++ b/Library/Homebrew/os/mac/xcode.rb
@@ -39,7 +39,7 @@ module MacOS::Xcode extend self
   end
 
   def without_clt?
-    version >= "4.3" and not MacOS::CLT.installed?
+    installed? && version >= "4.3" && !MacOS::CLT.installed?
   end
 
   def prefix