diff --git a/_plugins/jekyll-last-modified.rb b/_plugins/jekyll-last-modified.rb
index 4fd1860..fd189ac 100644
--- a/_plugins/jekyll-last-modified.rb
+++ b/_plugins/jekyll-last-modified.rb
@@ -1,3 +1,5 @@
+# Using https://github.com/michaelx/jekyll-last-modified
+
 module Jekyll
   class LastModifiedTag < Liquid::Tag