diff --git a/files/02show_upgraded b/files/02show_upgraded
index 870a3a9..eb046b2 100644
--- a/files/02show_upgraded
+++ b/files/02show_upgraded
@@ -1 +1,4 @@
+# This file is brought to you by Puppet
+# all local modifications will be overwritten
+
 APT::Get::Show-Upgraded true;
diff --git a/files/03clean b/files/03clean
index 335823d..d878375 100644
--- a/files/03clean
+++ b/files/03clean
@@ -1 +1,4 @@
+# This file is brought to you by Puppet
+# all local modifications will be overwritten
+
 DSelect::Clean auto;
diff --git a/templates/20proxy.erb b/templates/20proxy.erb
index e72319f..36b26a0 100644
--- a/templates/20proxy.erb
+++ b/templates/20proxy.erb
@@ -1 +1,4 @@
+# This file is brought to you by Puppet
+# all local modifications will be overwritten
+
 Acquire::http { Proxy "http://<%= real_apt_proxy %>:<%= real_apt_proxy_port %>"; };
diff --git a/templates/Debian/sources.list.erb b/templates/Debian/sources.list.erb
index 67da85d..7fb9bdf 100644
--- a/templates/Debian/sources.list.erb
+++ b/templates/Debian/sources.list.erb
@@ -1,4 +1,5 @@
 # This file is brought to you by puppet
+# all local modifications will be overwritten
 
 ### Debian current: <%= codename %>
 
diff --git a/templates/Ubuntu/sources.list.erb b/templates/Ubuntu/sources.list.erb
index 1486e95..2a25d6f 100644
--- a/templates/Ubuntu/sources.list.erb
+++ b/templates/Ubuntu/sources.list.erb
@@ -1,4 +1,5 @@
 # This file is brought to you by puppet
+# all local modifications will be overwritten
 
 # basic <%= lsbdistcodename %>
 deb <%= ubuntu_url %> <%= lsbdistcodename %> <%= repos %>