diff --git a/conf.c b/conf.c
index d3d58a7..404c7bc 100644
--- a/conf.c
+++ b/conf.c
@@ -665,8 +665,7 @@ static unsigned int conf_ip4(unsigned int ifi,
 	if (MAC_IS_ZERO(mac))
 		nl_link(0, ifi, mac, 0, 0);
 
-	if (IN4_IS_ADDR_UNSPECIFIED(&ip4->gw) ||
-	    IN4_IS_ADDR_UNSPECIFIED(&ip4->addr) ||
+	if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr) ||
 	    MAC_IS_ZERO(mac))
 		return 0;
 
@@ -708,7 +707,6 @@ static unsigned int conf_ip6(unsigned int ifi,
 		nl_link(0, ifi, mac, 0, 0);
 
 	if (IN6_IS_ADDR_UNSPECIFIED(&ip6->gw) ||
-	    IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) ||
 	    IN6_IS_ADDR_UNSPECIFIED(&ip6->addr_ll) ||
 	    MAC_IS_ZERO(mac))
 		return 0;
@@ -1660,6 +1658,12 @@ void conf(struct ctx *c, int argc, char **argv)
 	    (*c->ip6.ifname_out && !c->ifi6))
 		die("External interface not usable");
 
+	if (c->ifi4 && IN4_IS_ADDR_UNSPECIFIED(&c->ip4.gw))
+		c->no_map_gw = c->no_dhcp = 1;
+
+	if (c->ifi6 && IN6_IS_ADDR_UNSPECIFIED(&c->ip6.gw))
+		c->no_map_gw = 1;
+
 	/* Inbound port options can be parsed now (after IPv4/IPv6 settings) */
 	optind = 1;
 	do {
diff --git a/passt.1 b/passt.1
index ee2803a..96ce96e 100644
--- a/passt.1
+++ b/passt.1
@@ -281,7 +281,8 @@ guest or target namespace will be silently dropped.
 .TP
 .BR \-\-no-dhcp
 Disable the DHCP server. DHCP client requests coming from guest or target
-namespace will be silently dropped.
+namespace will be silently dropped. Implied if there is no gateway on the
+selected IPv4 default route.
 
 .TP
 .BR \-\-no-ndp
@@ -301,7 +302,8 @@ namespace will be ignored.
 .TP
 .BR \-\-no-map-gw
 Don't remap TCP connections and untracked UDP traffic, with the gateway address
-as destination, to the host.
+as destination, to the host. Implied if there is no gateway on the selected
+default route for any of the enabled address families.
 
 .TP
 .BR \-4 ", " \-\-ipv4-only