diff --git a/actionpack/lib/action_dispatch/http/parameters.rb b/actionpack/lib/action_dispatch/http/parameters.rb
index add8cab..772ab25 100644
--- a/actionpack/lib/action_dispatch/http/parameters.rb
+++ b/actionpack/lib/action_dispatch/http/parameters.rb
@@ -7,7 +7,7 @@ module ActionDispatch
       # Returns both GET and POST \parameters in a single hash.
       def parameters
         @env["action_dispatch.request.parameters"] ||= begin
-          params = request_parameters.merge(query_parameters)
+          params = request_parameters.merge(query_parameters || {})
           params.merge!(path_parameters)
           encode_params(params).with_indifferent_access
         end