diff --git a/lib/rucaptcha/controller_helpers.rb b/lib/rucaptcha/controller_helpers.rb
index 92cf1be..a76488f 100644
--- a/lib/rucaptcha/controller_helpers.rb
+++ b/lib/rucaptcha/controller_helpers.rb
@@ -8,7 +8,8 @@ module RuCaptcha
 
     # session key of rucaptcha
     def rucaptcha_sesion_key_key
-      ['rucaptcha-session', session.id].join(':')
+      session_id = session.respond_to?(:id) ? session.id : session[:session_id]
+      ['rucaptcha-session', session_id].join(':')
     end
 
     # Generate a new Captcha