diff --git a/lib/chartkick/engine.rb b/lib/chartkick/engine.rb
index 33bedce..520bcc8 100644
--- a/lib/chartkick/engine.rb
+++ b/lib/chartkick/engine.rb
@@ -4,7 +4,7 @@ class Engine < ::Rails::Engine
 
     # for importmap
     initializer "chartkick.importmap" do |app|
-      if defined?(Importmap)
+      if defined?(Importmap) && defined?(Sprockets)
         app.config.assets.precompile << "chartkick.js"
         app.config.assets.precompile << "Chart.bundle.js"
       end