diff --git a/src/sources/portknock.c b/src/sources/portknock.c
index 2b85f0b..dd2ac4b 100644
--- a/src/sources/portknock.c
+++ b/src/sources/portknock.c
@@ -144,6 +144,7 @@ start(cfg_t *cfg) {
   for (f2b_port_t *port = cfg->ports; port != 0; port = port->next) {
     port->sock = -1;
     int ret = getaddrinfo(port->host, port->port, &hints, &result);
+    int opt = 1;
     if (ret != 0) {
       snprintf(cfg->error, sizeof(cfg->error), "getaddrinfo: %s", gai_strerror(ret));
       cfg->errcb(cfg->error);
@@ -153,6 +154,7 @@ start(cfg_t *cfg) {
       port->sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
       if (port->sock == -1)
         continue;
+      setsockopt(port->sock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
       if (bind(port->sock, rp->ai_addr, rp->ai_addrlen) == 0) {
         if (listen(port->sock, 5) == 0) /* TODO: hardcoded */
           break; /* success */