diff --git a/lib/omniauth/strategies/flowdock.rb b/lib/omniauth/strategies/flowdock.rb
index a77034b..d8a1606 100644
--- a/lib/omniauth/strategies/flowdock.rb
+++ b/lib/omniauth/strategies/flowdock.rb
@@ -25,6 +25,10 @@ class Flowdock < OmniAuth::Strategies::OAuth2
       def raw_info
         @raw_info ||= access_token.get('user').parsed
       end
+
+      def callback_url
+        full_host + script_name + callback_path
+      end
     end
   end
 end