diff --git a/plugins/nginx/nginx_vhost_traffic b/plugins/nginx/nginx_vhost_traffic
index e2f710fe..4b3a94d9 100755
--- a/plugins/nginx/nginx_vhost_traffic
+++ b/plugins/nginx/nginx_vhost_traffic
@@ -35,7 +35,7 @@ ACCESS_LOG=$LOGDIR/${logfile:-access.log}
 LOGTAIL=${logtail:-`which logtail`}
 STATEFILE=$MUNIN_PLUGSTATE/nginx_vhost_traffic.state
 VHOSTS=${vhosts:-`hostname`}
-AGGREGATE=${aggregate:true}
+AGGREGATE=${aggregate:-true}
 
 BPARAM=${bparam:-11}