diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 020594f0c5..29d2e342f7 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -789,7 +789,7 @@ module Homebrew
         return if ENV["CI"] || ENV["JENKINS_HOME"]
 
         branch = coretap_path.git_branch
-        return if branch.nil? || branch =~ %r{master}
+        return if branch.nil? || branch =~ /master/
 
 
         <<-EOS.undent