diff --git a/Shorewall/hosts b/Shorewall/hosts
index e23e9f712..91838455a 100644
--- a/Shorewall/hosts
+++ b/Shorewall/hosts
@@ -19,6 +19,9 @@
 #			b) A subnetwork in the form
 #			   <subnet-address>/<mask width>
 #		  
+#		  The interface must be defined in the
+#		  /etc/shorewall/interfaces file.
+#
 #		  Examples:
 #
 #			eth1:192.168.1.3