diff --git a/middleman-core/lib/middleman-core/load_paths.rb b/middleman-core/lib/middleman-core/load_paths.rb
index 7daffe4c..d8937864 100644
--- a/middleman-core/lib/middleman-core/load_paths.rb
+++ b/middleman-core/lib/middleman-core/load_paths.rb
@@ -22,7 +22,7 @@ module Middleman
 
     # Set BUNDLE_GEMFILE and run Bundler setup. Raises an exception if there is no Gemfile
     def setup_bundler
-      ENV['BUNDLE_GEMFILE'] ||= findup('Gemfile', ENV['MM_ROOT'])
+      ENV['BUNDLE_GEMFILE'] ||= File.join(findup('Gemfile', ENV['MM_ROOT']), "Gemfile")
 
       unless File.exist?(ENV['BUNDLE_GEMFILE'])
         ENV['BUNDLE_GEMFILE'] = File.expand_path('../../../../Gemfile', __FILE__)