diff --git a/doc/install-guide/ch_debconf.xml b/doc/install-guide/ch_debconf.xml
index 4333ba057f..850bc1ec3b 100644
--- a/doc/install-guide/ch_debconf.xml
+++ b/doc/install-guide/ch_debconf.xml
@@ -3,7 +3,8 @@
   xmlns:xi="http://www.w3.org/2001/XInclude"
   xmlns:xlink="http://www.w3.org/1999/xlink"
   version="5.0"
-  xml:id="ch_debconf">
+  xml:id="ch_debconf"
+  os="debian">
     <title>Configure OpenStack with debconf</title>
     <xi:include href="section_debconf-concepts.xml"/>
     <xi:include href="section_debconf-dbconfig-common.xml"/>