diff --git a/lib/puppet-strings/markdown.rb b/lib/puppet-strings/markdown.rb
index c3cebee..6a9f33c 100644
--- a/lib/puppet-strings/markdown.rb
+++ b/lib/puppet-strings/markdown.rb
@@ -13,7 +13,8 @@ module PuppetStrings::Markdown
   # generates markdown documentation
   # @return [String] markdown doc
   def self.generate
-    final = "# Reference\n\n"
+    final = "# Reference\n"
+    final << "<!-- DO NOT EDIT: This document was generated by Puppet Strings -->\n\n"
     final << PuppetStrings::Markdown::TableOfContents.render
     final << PuppetStrings::Markdown::PuppetClasses.render
     final << PuppetStrings::Markdown::DefinedTypes.render
diff --git a/spec/fixtures/unit/markdown/output.md b/spec/fixtures/unit/markdown/output.md
index 307c620..7ebc635 100644
--- a/spec/fixtures/unit/markdown/output.md
+++ b/spec/fixtures/unit/markdown/output.md
@@ -1,4 +1,5 @@
 # Reference
+<!-- DO NOT EDIT: This document was generated by Puppet Strings -->
 
 ## Classes
 
diff --git a/spec/fixtures/unit/markdown/output_with_plan.md b/spec/fixtures/unit/markdown/output_with_plan.md
index b00ef0f..9ca179a 100644
--- a/spec/fixtures/unit/markdown/output_with_plan.md
+++ b/spec/fixtures/unit/markdown/output_with_plan.md
@@ -1,4 +1,5 @@
 # Reference
+<!-- DO NOT EDIT: This document was generated by Puppet Strings -->
 
 ## Classes