diff --git a/setup.rb b/setup.rb
index 16ffa7215..49f6bfca5 100644
--- a/setup.rb
+++ b/setup.rb
@@ -24,6 +24,12 @@ require 'rubygems/exceptions'
Gem::CommandManager.instance.register_command :setup
+require 'rubygems/commands/setup_command'
+
+class Gem::Commands::SetupCommand
+ def install_default_bundler_gem(bin_dir); end
+end
+
args = ARGV.clone
if ENV["GEM_PREV_VER"]
args = [ "--previous-version", ENV["GEM_PREV_VER"] ] + args