diff --git a/ntpd/templates/ntp.conf.erb b/ntpd/templates/ntp.conf.erb
index 9e978db..46a76ea 100644
--- a/ntpd/templates/ntp.conf.erb
+++ b/ntpd/templates/ntp.conf.erb
@@ -26,7 +26,7 @@ server <%= server %>
 server 127.127.1.0
 fudge  127.127.1.0 stratum 10
 <% end -%>
-<% if ntp_client_networks -%>
+<% if defined?("ntp_client_networks") -%>
 
 # Restrictions for clients using us as source.
 <%     ntp_client_networks.each do |net| -%>