diff --git a/lib/typescript/rails/railtie.rb b/lib/typescript/rails/railtie.rb
index 99f3524..2e7b2f2 100644
--- a/lib/typescript/rails/railtie.rb
+++ b/lib/typescript/rails/railtie.rb
@@ -12,7 +12,7 @@ class Typescript::Rails::Railtie < ::Rails::Railtie
       end
 
       if Sprockets.respond_to?(:register_transformer)
-        Sprockets.register_mime_type 'text/typescript', extensions: ['.js.ts']
+        Sprockets.register_mime_type 'text/typescript', extensions: ['.ts']
         Sprockets.register_transformer 'text/typescript', 'application/javascript', Typescript::Rails::Transformer
       end
     end