diff --git a/lib/devise/mapping.rb b/lib/devise/mapping.rb
index 8b1f94ced..cb4a2316e 100644
--- a/lib/devise/mapping.rb
+++ b/lib/devise/mapping.rb
@@ -33,7 +33,9 @@ class Mapping #:nodoc:
     # Receives an object and finds a scope for it. If a scope cannot be found,
     # raises an error. If a symbol is given, it's considered to be the scope.
     def self.find_scope!(obj)
+      Rails.application.try(:reload_routes_unless_loaded)
       obj = obj.devise_scope if obj.respond_to?(:devise_scope)
+
       case obj
       when String, Symbol
         return obj.to_sym