diff --git a/lib/shakapacker/railtie.rb b/lib/shakapacker/railtie.rb
index d73fe259..6ae9cde6 100644
--- a/lib/shakapacker/railtie.rb
+++ b/lib/shakapacker/railtie.rb
@@ -3,6 +3,7 @@
 require "shakapacker/helper"
 require "shakapacker/dev_server_proxy"
 require "shakapacker/version_checker"
+require "shakapacker/utils/manager"
 
 class Shakapacker::Engine < ::Rails::Engine
   # Allows Shakapacker config values to be set via Rails env config files
@@ -14,6 +15,12 @@ class Shakapacker::Engine < ::Rails::Engine
     end
   end
 
+  initializer "shakapacker.manager_checker" do
+    if File.exist?(Shakapacker::VersionChecker::NodePackageVersion.package_json_path)
+      Shakapacker::Utils::Manager.error_unless_package_manager_is_obvious!
+    end
+  end
+
   initializer "shakapacker.proxy" do |app|
     if (Shakapacker.config.dev_server.present? rescue nil)
       app.middleware.insert_before 0,