diff --git a/tool/redmine-backporter.rb b/tool/redmine-backporter.rb
index 38ebf55fed..8299872d2f 100755
--- a/tool/redmine-backporter.rb
+++ b/tool/redmine-backporter.rb
@@ -215,7 +215,7 @@ class << Readline
     console.print prompt
     console.flush
     line = ''
-    while 1
+    while true
       case c = console.getch
       when "\r", "\n"
         puts