diff --git a/conf.c b/conf.c
index 3f30725..21d46fe 100644
--- a/conf.c
+++ b/conf.c
@@ -1203,8 +1203,8 @@ void conf(struct ctx *c, int argc, char **argv)
 		optstring = "dqfel:hs:F:p:P:m:a:n:M:g:i:o:D:S:461t:u:";
 	}
 
-	c->tcp.fwd_in.mode = c->tcp.fwd_out.mode = 0;
-	c->udp.fwd_in.f.mode = c->udp.fwd_out.f.mode = 0;
+	c->tcp.fwd_in.mode = c->tcp.fwd_out.mode = FWD_UNSET;
+	c->udp.fwd_in.f.mode = c->udp.fwd_out.f.mode = FWD_UNSET;
 
 	do {
 		name = getopt_long(argc, argv, optstring, options, NULL);
diff --git a/fwd.h b/fwd.h
index 23281d9..41645d7 100644
--- a/fwd.h
+++ b/fwd.h
@@ -11,6 +11,7 @@
 #define	NUM_PORTS	(1U << 16)
 
 enum fwd_ports_mode {
+	FWD_UNSET = 0,
 	FWD_SPEC = 1,
 	FWD_NONE,
 	FWD_AUTO,