diff --git a/Library/Homebrew/os/mac/xquartz.rb b/Library/Homebrew/os/mac/xquartz.rb
index dfb8afee7c..9a610e29fd 100644
--- a/Library/Homebrew/os/mac/xquartz.rb
+++ b/Library/Homebrew/os/mac/xquartz.rb
@@ -5,9 +5,9 @@ module OS
     module XQuartz
       extend self
 
-      FORGE_BUNDLE_ID = "org.macosforge.xquartz.X11"
-      APPLE_BUNDLE_ID = "org.x.X11"
-      FORGE_PKG_ID = "org.macosforge.xquartz.pkg"
+      FORGE_BUNDLE_ID = "org.macosforge.xquartz.X11".freeze
+      APPLE_BUNDLE_ID = "org.x.X11".freeze
+      FORGE_PKG_ID = "org.macosforge.xquartz.pkg".freeze
 
       PKGINFO_VERSION_MAP = {
         "2.6.34" => "2.6.3",