diff --git a/zapret/config.default b/zapret/config.default
index 1f804f0..c0d26ce 100644
--- a/zapret/config.default
+++ b/zapret/config.default
@@ -90,8 +90,8 @@ NFQWS_UDP_PKT_IN="0"
 # normally it's needed only for stateless DPI that matches every packet in a single TCP session
 # typical example are plain HTTP keep alives
 # this mode can be very CPU consuming. enable with care !
-NFQWS_PORTS_TCP_KEEPALIVE=0
-NFQWS_PORTS_UDP_KEEPALIVE=0
+NFQWS_PORTS_TCP_KEEPALIVE=""
+NFQWS_PORTS_UDP_KEEPALIVE=""
 
 # use <HOSTLIST> and <HOSTLIST_NOAUTO> placeholders to engage standard hostlists and autohostlist in ipset dir
 # hostlist markers are replaced to empty string if MODE_FILTER does not satisfy
diff --git a/zapret/sync_config.sh b/zapret/sync_config.sh
index cd3cdaa..f7f99b3 100755
--- a/zapret/sync_config.sh
+++ b/zapret/sync_config.sh
@@ -48,6 +48,9 @@ function sync_param
 	if [ "$value" = "$TAB" ]; then
 		value=""
 	fi
+	if [ "$param" = "NFQWS_PORTS_TCP_KEEPALIVE" -o "$param" = "NFQWS_PORTS_UDP_KEEPALIVE" ]; then
+		[ "$value" = "0" ] && value=""
+	fi
 	if [ "$vtype" = "str" ]; then
 		set_param_value_str $param "$value"
 	else
@@ -94,8 +97,8 @@ sync_param NFQWS_TCP_PKT_OUT str
 sync_param NFQWS_TCP_PKT_IN str
 sync_param NFQWS_UDP_PKT_OUT str
 sync_param NFQWS_UDP_PKT_IN str
-sync_param NFQWS_PORTS_TCP_KEEPALIVE
-sync_param NFQWS_PORTS_UDP_KEEPALIVE
+sync_param NFQWS_PORTS_TCP_KEEPALIVE str
+sync_param NFQWS_PORTS_UDP_KEEPALIVE str
 sync_param NFQWS_OPT str
 
 ZAPRET_CONFIG="$ZAPRET_CONFIG__SAVED"