diff --git a/lib/heartcheck/checks/firewall.rb b/lib/heartcheck/checks/firewall.rb
index 31f5613..1ecca70 100644
--- a/lib/heartcheck/checks/firewall.rb
+++ b/lib/heartcheck/checks/firewall.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: true
+# frozen_string_literal: false
 
 module Heartcheck
   module Checks