diff --git a/Library/Homebrew/macos.rb b/Library/Homebrew/macos.rb
index d44b7627ab..1db630619d 100644
--- a/Library/Homebrew/macos.rb
+++ b/Library/Homebrew/macos.rb
@@ -174,7 +174,7 @@ module MacOS extend self
     # distributed by Apple is also XQuartz, and therefore covered by this method.
     path = app_with_bundle_id(XQUARTZ_BUNDLE_ID) || app_with_bundle_id(APPLE_X11_BUNDLE_ID)
     version = if not path.nil? and path.exist?
-      `mdls -raw -name kMDItemVersion #{path}`.strip
+      `mdls -raw -name kMDItemVersion "#{path}" 2>/dev/null`.strip
     end
   end