diff --git a/Library/Homebrew/requirements.rb b/Library/Homebrew/requirements.rb
index 68d21a2b7a44b5d573421b0e876ed88d1faf4162..3774319eea6d159c437065149457b3da7f7f5a8d 100644
--- a/Library/Homebrew/requirements.rb
+++ b/Library/Homebrew/requirements.rb
@@ -39,11 +39,11 @@ class XcodeRequirement < Requirement
       Installing just the Command Line Tools is not sufficient.
     EOS
     if MacOS.version >= :lion
-      message += <<-EOS.undent
+      message + <<-EOS.undent
         Xcode can be installed from the App Store.
       EOS
     else
-      message += <<-EOS.undent
+      message + <<-EOS.undent
         Xcode can be installed from https://developer.apple.com/xcode/downloads/
       EOS
     end