diff --git a/lib/rubygems/commands/setup_command.rb b/lib/rubygems/commands/setup_command.rb
index 8368e3ac7a..055f329a5d 100644
--- a/lib/rubygems/commands/setup_command.rb
+++ b/lib/rubygems/commands/setup_command.rb
@@ -604,6 +604,9 @@ abort "#{deprecation_message}"
 
       to_remove = old_lib_files - lib_files
 
+      gauntlet_rubygems = File.join(lib_dir, 'gauntlet_rubygems.rb')
+      to_remove << gauntlet_rubygems if File.exist? gauntlet_rubygems
+
       to_remove.delete_if do |file|
         file.start_with? 'defaults'
       end
diff --git a/test/rubygems/test_gem_commands_setup_command.rb b/test/rubygems/test_gem_commands_setup_command.rb
index e0a6c0c94c..9ebe2a37e8 100644
--- a/test/rubygems/test_gem_commands_setup_command.rb
+++ b/test/rubygems/test_gem_commands_setup_command.rb
@@ -277,11 +277,13 @@ class TestGemCommandsSetupCommand < Gem::TestCase
     engine_defaults_rb = File.join lib_rubygems_defaults, 'jruby.rb'
     os_defaults_rb     = File.join lib_rubygems_defaults, 'operating_system.rb'
 
+    old_gauntlet_rubygems_rb = File.join lib, 'gauntlet_rubygems.rb'
+
     old_builder_rb     = File.join lib_rubygems, 'builder.rb'
     old_format_rb      = File.join lib_rubygems, 'format.rb'
     old_bundler_c_rb   = File.join lib_bundler,  'c.rb'
 
-    files_that_go   = [old_builder_rb, old_format_rb, old_bundler_c_rb]
+    files_that_go   = [old_gauntlet_rubygems_rb, old_builder_rb, old_format_rb, old_bundler_c_rb]
     files_that_stay = [securerandom_rb, engine_defaults_rb, os_defaults_rb]
 
     create_dummy_files(files_that_go + files_that_stay)