diff --git a/spec/defines/source_spec.rb b/spec/defines/source_spec.rb
index 34b3942..bf5e50e 100644
--- a/spec/defines/source_spec.rb
+++ b/spec/defines/source_spec.rb
@@ -74,7 +74,7 @@ describe 'apt::source', :type => :define do
       end
 
       let :content do
-        content = "# #{title}"
+        content = "#file generated by puppet\n# #{title}"
         if param_hash[:architecture]
           arch = "[arch=#{param_hash[:architecture]}] "
         end
diff --git a/templates/source.list.erb b/templates/source.list.erb
index 9946966..541534e 100644
--- a/templates/source.list.erb
+++ b/templates/source.list.erb
@@ -1,3 +1,4 @@
+#file generated by puppet
 # <%= @name %>
 deb <% if @architecture %>[arch=<%= @architecture %>] <% end %><%= @location %> <%= @release_real %> <%= @repos %>
 <%- if @include_src then -%>