diff --git a/lib/jekyll/plugin_manager.rb b/lib/jekyll/plugin_manager.rb
index e709b608..b48969fe 100644
--- a/lib/jekyll/plugin_manager.rb
+++ b/lib/jekyll/plugin_manager.rb
@@ -33,7 +33,7 @@ module Jekyll
     end
 
     def self.require_from_bundler
-      if ENV["JEKYLL_NO_BUNDLER_REQUIRE"]
+      if ENV["JEKYLL_NO_BUNDLER_REQUIRE"] || !File.file?("Gemfile")
         false
       else
         require "bundler"