diff --git a/lib/requirejs/rails/config.rb b/lib/requirejs/rails/config.rb
index 93862abf..aa039987 100644
--- a/lib/requirejs/rails/config.rb
+++ b/lib/requirejs/rails/config.rb
@@ -88,7 +88,7 @@ def initialize(application)
         uglify
         uglify2
         useStrict
-        wrap
+        wrapShim
       }
       end
 
@@ -133,6 +133,9 @@ def user_config=(cfg)
         if url = cfg.delete('baseUrl')
           raise Requirejs::ConfigError, "baseUrl is not needed or permitted in the configuration"
         end
+        # delete any cached configs, will be lazily resolved
+        self.delete(:build_config)
+        self.delete(:run_config)
         self[:user_config] = cfg
       end