diff --git a/daemon/call.c b/daemon/call.c
index 1b446bc..a5ca9a7 100644
--- a/daemon/call.c
+++ b/daemon/call.c
@@ -2206,3 +2206,9 @@ const char *call_delete_ng(bencode_item_t *input, struct callmaster *m, bencode_
 	bencode_dictionary_add_string(output, "result", "ok");
 	return NULL;
 }
+
+void callmaster_exclude_port(struct callmaster *m, u_int16_t p) {
+	mutex_lock(&m->portlock);
+	bit_array_set(m->ports_used, p);
+	mutex_unlock(&m->portlock);
+}
diff --git a/daemon/call.h b/daemon/call.h
index ba1d58e..21fad23 100644
--- a/daemon/call.h
+++ b/daemon/call.h
@@ -131,6 +131,7 @@ struct callmaster;
 
 struct callmaster *callmaster_new(struct poller *);
 void callmaster_config(struct callmaster *m, struct callmaster_config *c);
+void callmaster_exclude_port(struct callmaster *m, u_int16_t p);
 
 
 str *call_request_tcp(char **, struct callmaster *);
diff --git a/daemon/main.c b/daemon/main.c
index bf58a38..e7a635d 100644
--- a/daemon/main.c
+++ b/daemon/main.c
@@ -423,6 +423,7 @@ void create_everything(struct main_context *ctx) {
 
 	cu = NULL;
 	if (udp_listenport) {
+		callmaster_exclude_port(ctx->m, udp_listenport);
 		cu = control_udp_new(ctx->p, udp_listenp, udp_listenport, ctx->m);
 		if (!cu)
 			die("Failed to open UDP control connection port\n");
@@ -430,6 +431,7 @@ void create_everything(struct main_context *ctx) {
 
 	cn = NULL;
 	if (ng_listenport) {
+		callmaster_exclude_port(ctx->m, ng_listenport);
 		cn = control_ng_new(ctx->p, ng_listenp, ng_listenport, ctx->m);
 		if (!cn)
 			die("Failed to open UDP control connection port\n");