diff --git a/examples/mip-pcap/main.c b/examples/mip-pcap/main.c
index 2861745a..44c50218 100644
--- a/examples/mip-pcap/main.c
+++ b/examples/mip-pcap/main.c
@@ -9,6 +9,10 @@
 #define MQTT_URL "mqtt://broker.hivemq.com:1883"  // MQTT broker to connect to
 #define MQTT_TOPIC "t/123"                        // Topic to subscribe to
 
+#if MG_ARCH == MG_ARCH_WIN32
+#define usleep(x) Sleep((x) / 1000)
+#endif
+
 static int s_signo;
 void signal_handler(int signo) {
   s_signo = signo;
@@ -30,7 +34,7 @@ static size_t pcap_rx(void *buf, size_t len, void *userdata) {
   size_t received = 0;
   struct pcap_pkthdr *hdr = NULL;
   const unsigned char *pkt = NULL;
-  usleep(1); // This is to avoid 100% CPU
+  usleep(1000);  // Sleep 1 millisecond. This is to avoid 100% CPU
   if (pcap_next_ex((pcap_t *) userdata, &hdr, &pkt) == 1) {  // Yes, read
     received = hdr->len < len ? hdr->len : len;
     memcpy(buf, pkt, received);
@@ -53,7 +57,7 @@ int main(int argc, char *argv[]) {
     } else if (strcmp(argv[i], "-bpf") == 0 && i + 1 < argc) {
       bpf = argv[++i];
     } else if (strcmp(argv[i], "-v") == 0 && i + 1 < argc) {
-      mg_log_set(atoi(argv[++i])); 
+      mg_log_set(atoi(argv[++i]));
     } else {
       MG_ERROR(("unknown option %s", argv[i]));
       return EXIT_FAILURE;
@@ -88,8 +92,8 @@ int main(int argc, char *argv[]) {
   signal(SIGINT, signal_handler);
   signal(SIGTERM, signal_handler);
 
-  struct mg_mgr mgr;        // Event manager
-  mg_mgr_init(&mgr);        // Initialise event manager
+  struct mg_mgr mgr;  // Event manager
+  mg_mgr_init(&mgr);  // Initialise event manager
 
   struct mip_cfg c = {.ip = 0, .mask = 0, .gw = 0};
   sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx", &c.mac[0], &c.mac[1], &c.mac[2],
diff --git a/mip/mip.c b/mip/mip.c
index be3dbaff..77487da1 100644
--- a/mip/mip.c
+++ b/mip/mip.c
@@ -28,6 +28,7 @@ struct connstate {
   uint8_t ttype;               // Timer type. 0: ack, 1: keep-alive
 #define MIP_TTYPE_KEEPALIVE 0  // Connection is idle for long, send keepalive
 #define MIP_TTYPE_ACK 1        // Peer sent us data, we have to ack it soon
+  uint8_t tmiss;               // Number of keep-alive misses
   struct mg_iobuf raw;         // For TLS only. Incoming raw data
 };
 
@@ -319,7 +320,7 @@ static void onstatechange(struct mip_if *ifp) {
   if (ifp->state == MIP_STATE_READY) {
     MG_INFO(("READY, IP: %M", mg_print_ipv4, ifp->ip));
     MG_INFO(("       GW: %M", mg_print_ipv4, ifp->gw));
-    MG_INFO(("       Lease: %lld sec", (ifp->lease_expire - ifp->now)/1000));
+    MG_INFO(("       Lease: %lld sec", (ifp->lease_expire - ifp->now) / 1000));
     arp_ask(ifp, ifp->gw);
   } else if (ifp->state == MIP_STATE_UP) {
     MG_ERROR(("Link up"));
@@ -660,7 +661,8 @@ static void rx_tcp(struct mip_if *ifp, struct pkt *pkt) {
   struct connstate *s = (struct connstate *) (c + 1);
 
   if (c != NULL && s->ttype == MIP_TTYPE_KEEPALIVE) {
-    settmout(c, MIP_TTYPE_KEEPALIVE);
+    s->tmiss = 0;                      // Reset missed keep-alive counter
+    settmout(c, MIP_TTYPE_KEEPALIVE);  // Advance keep-alive timer
   }
 #if 0
   MG_INFO(("%lu %hhu %d", c ? c->id : 0, pkt->tcp->flags, (int) pkt->pay.len));
@@ -827,6 +829,7 @@ static void mip_poll(struct mip_if *ifp, uint64_t uptime_ms) {
         MG_DEBUG(("%lu keepalive", c->id));
         tx_tcp(ifp, c->rem.ip, TH_ACK, c->loc.port, c->rem.port,
                mg_htonl(s->seq - 1), mg_htonl(s->ack), "", 0);
+        if (s->tmiss++ > 2) mg_error(c, "keepalive");
       }
       settmout(c, MIP_TTYPE_KEEPALIVE);
     }
diff --git a/mongoose.c b/mongoose.c
index 2c0249ee..f606da31 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -2357,7 +2357,7 @@ int mg_iobuf_resize(struct mg_iobuf *io, size_t new_size) {
     void *p = calloc(1, new_size);
     if (p != NULL) {
       size_t len = new_size < io->len ? new_size : io->len;
-      if (len > 0) memmove(p, io->buf, len);
+      if (len > 0 && io->buf != NULL) memmove(p, io->buf, len);
       zeromem(io->buf, io->size);
       free(io->buf);
       io->buf = (unsigned char *) p;
@@ -6317,6 +6317,7 @@ struct connstate {
   uint8_t ttype;               // Timer type. 0: ack, 1: keep-alive
 #define MIP_TTYPE_KEEPALIVE 0  // Connection is idle for long, send keepalive
 #define MIP_TTYPE_ACK 1        // Peer sent us data, we have to ack it soon
+  uint8_t tmiss;               // Number of keep-alive misses
   struct mg_iobuf raw;         // For TLS only. Incoming raw data
 };
 
@@ -6608,7 +6609,7 @@ static void onstatechange(struct mip_if *ifp) {
   if (ifp->state == MIP_STATE_READY) {
     MG_INFO(("READY, IP: %M", mg_print_ipv4, ifp->ip));
     MG_INFO(("       GW: %M", mg_print_ipv4, ifp->gw));
-    MG_INFO(("       Lease: %lld sec", (ifp->lease_expire - ifp->now)/1000));
+    MG_INFO(("       Lease: %lld sec", (ifp->lease_expire - ifp->now) / 1000));
     arp_ask(ifp, ifp->gw);
   } else if (ifp->state == MIP_STATE_UP) {
     MG_ERROR(("Link up"));
@@ -6949,7 +6950,8 @@ static void rx_tcp(struct mip_if *ifp, struct pkt *pkt) {
   struct connstate *s = (struct connstate *) (c + 1);
 
   if (c != NULL && s->ttype == MIP_TTYPE_KEEPALIVE) {
-    settmout(c, MIP_TTYPE_KEEPALIVE);
+    s->tmiss = 0;                      // Reset missed keep-alive counter
+    settmout(c, MIP_TTYPE_KEEPALIVE);  // Advance keep-alive timer
   }
 #if 0
   MG_INFO(("%lu %hhu %d", c ? c->id : 0, pkt->tcp->flags, (int) pkt->pay.len));
@@ -7116,6 +7118,7 @@ static void mip_poll(struct mip_if *ifp, uint64_t uptime_ms) {
         MG_DEBUG(("%lu keepalive", c->id));
         tx_tcp(ifp, c->rem.ip, TH_ACK, c->loc.port, c->rem.port,
                mg_htonl(s->seq - 1), mg_htonl(s->ack), "", 0);
+        if (s->tmiss++ > 2) mg_error(c, "keepalive");
       }
       settmout(c, MIP_TTYPE_KEEPALIVE);
     }