diff --git a/actionpack/test/dispatch/request/query_string_parsing_test.rb b/actionpack/test/dispatch/request/query_string_parsing_test.rb
index d82493140f..4e99c26e03 100644
--- a/actionpack/test/dispatch/request/query_string_parsing_test.rb
+++ b/actionpack/test/dispatch/request/query_string_parsing_test.rb
@@ -105,6 +105,7 @@ class QueryStringParsingTest < ActionDispatch::IntegrationTest
   end
 
   test "perform_deep_munge" do
+    old_perform_deep_munge = ActionDispatch::Request::Utils.perform_deep_munge
     ActionDispatch::Request::Utils.perform_deep_munge = false
     begin
       assert_parses({"action" => nil}, "action")
@@ -115,7 +116,7 @@ class QueryStringParsingTest < ActionDispatch::IntegrationTest
       assert_parses({"action" => {"foo" => [{"bar" => nil}]}}, "action[foo][][bar]")
       assert_parses({"action" => ['1',nil]}, "action[]=1&action[]")
     ensure
-      ActionDispatch::Request::Utils.perform_deep_munge = true
+      ActionDispatch::Request::Utils.perform_deep_munge = old_perform_deep_munge
     end
   end