diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 30d5eecff8..3e979a46ad 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -2686,7 +2686,7 @@ static int proxy_update(struct sip_proxy *proxy)
 static int port_str2int(const char *pt, unsigned int standard)
 {
 	int port = standard;
-	if (ast_strlen_zero(pt) || (sscanf(pt, "%30d", &port) != 1) || (port < 0)) {
+	if (ast_strlen_zero(pt) || (sscanf(pt, "%30d", &port) != 1) || (port < 1) || (port > 65535)) {
 		port = standard;
 	}