diff --git a/lib/puma/control_cli.rb b/lib/puma/control_cli.rb
index bd8fd4d7..364b532a 100644
--- a/lib/puma/control_cli.rb
+++ b/lib/puma/control_cli.rb
@@ -263,7 +263,7 @@ module Puma
       events = Puma::Events.new @stdout, @stderr
 
       # replace $0 because puma use it to generate restart command
-      puma_cmd = $0.gsub /pumactl$/, 'puma'
+      puma_cmd = $0.gsub(/pumactl$/, 'puma')
       $0 = puma_cmd if File.exist?(puma_cmd)
 
       cli = Puma::CLI.new run_args, events