diff --git a/activesupport/lib/active_support/string_inquirer.rb b/activesupport/lib/active_support/string_inquirer.rb
index cd722a3cfb23b474b4c27a20ab2c1f8e76830505..e6b1f392251d726efce7fc4b19ef9fb4aca36d81 100644
--- a/activesupport/lib/active_support/string_inquirer.rb
+++ b/activesupport/lib/active_support/string_inquirer.rb
@@ -11,7 +11,7 @@ module ActiveSupport
   #
   class StringInquirer < String
     def method_missing(method_name, *arguments)
-      if method_name.to_s.ends_with?("?")
+      if method_name.to_s[-1,1] == "?"
         self == method_name.to_s[0..-2]
       else
         super