diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 9828529634b..99fcd1f90a8 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -903,6 +903,9 @@ sysctl_net_inet_tcp_udp_tunneling_port_check(SYSCTL_HANDLER_ARGS)
 			}
 			if (new != 0) {
 				error = tcp_over_udp_start();
+				if (error != 0) {
+					V_tcp_udp_tunneling_port = 0;
+				}
 			}
 			sx_xunlock(&tcpoudp_lock);
 		}