diff --git a/actionpack/lib/action_controller/rack_ext/parse_query.rb b/actionpack/lib/action_controller/rack_ext/parse_query.rb
index 2f21a57770fad..b1acef8e721e3 100644
--- a/actionpack/lib/action_controller/rack_ext/parse_query.rb
+++ b/actionpack/lib/action_controller/rack_ext/parse_query.rb
@@ -10,7 +10,6 @@ module Utils
     def parse_query(qs, d = '&;')
       qs = qs.dup
       qs.chop! if qs[-1] == 0
-      qs.gsub!(/&_=$/, '')
       parse_query_without_ajax_body_cleanup(qs, d)
     end
     module_function :parse_query
diff --git a/actionpack/test/controller/request/url_encoded_params_parsing_test.rb b/actionpack/test/controller/request/url_encoded_params_parsing_test.rb
index 89239687de782..90865afc4ec0a 100644
--- a/actionpack/test/controller/request/url_encoded_params_parsing_test.rb
+++ b/actionpack/test/controller/request/url_encoded_params_parsing_test.rb
@@ -156,12 +156,6 @@ def teardown
     assert_parses expected, query
   end
 
-  test "parses params with Prototype's hack around Safari 2 trailing null character" do
-    query = "selected[]=1&selected[]=2&selected[]=3&_="
-    expected = { "selected" => [ "1", "2", "3" ] }
-    assert_parses expected, query
-  end
-
   test "passes through rack middleware and parses params" do
     with_muck_middleware do
       assert_parses({ "a" => { "b" => "c" } }, "a[b]=c")