diff --git a/src/wolfip.c b/src/wolfip.c
index 9fcfdb2..18cd706 100644
--- a/src/wolfip.c
+++ b/src/wolfip.c
@@ -123,7 +123,8 @@ struct wolfIP_icmp_packet;
 
 struct PACKED pkt_desc {
     uint32_t pos, len;
-    uint16_t flags, time_sent;
+    uint32_t flags;
+    uint32_t time_sent;
 };
 
 struct fifo {
@@ -955,6 +956,13 @@ static inline struct ipconf *wolfIP_primary_ipconf(struct wolfIP *s)
     return wolfIP_ipconf_at(s, WOLFIP_PRIMARY_IF_IDX);
 }
 
+static inline uint16_t ipcounter_next(struct wolfIP *s)
+{
+    uint16_t id = s->ipcounter;
+    s->ipcounter = (uint16_t)(id + 1);
+    return ee16(id);
+}
+
 static inline int ip_is_local_conf(const struct ipconf *conf, ip4 addr)
 {
     if (!conf)
@@ -1141,7 +1149,7 @@ static void wolfIP_send_ttl_exceeded(struct wolfIP *s, unsigned int if_idx, stru
     icmp.ip.ver_ihl = 0x45;
     icmp.ip.ttl = 64;
     icmp.ip.proto = WI_IPPROTO_ICMP;
-    icmp.ip.id = ee16(s->ipcounter++);
+    icmp.ip.id = ipcounter_next(s);
     icmp.ip.len = ee16(IP_HEADER_LEN + ICMP_TTL_EXCEEDED_SIZE);
     icmp.ip.src = ee32(wolfIP_ipconf_at(s, if_idx)->ip);
     icmp.ip.dst = orig->src;
@@ -1558,6 +1566,14 @@ static void tcp_send_syn(struct tsocket *t, uint8_t flags)
     fifo_push(&t->sock.tcp.txbuf, tcp, sizeof(struct wolfIP_tcp_seg) + opt_len);
 }
 
+/* Increment a TCP sequence number (wraps at 2^32) */
+static inline uint32_t tcp_seq_inc(uint32_t seq, uint32_t n)
+{
+    if (n > UINT32_MAX - seq)
+        return n - (UINT32_MAX - seq) - 1;
+    return seq + n;
+}
+
 /* Add a segment to the rx buffer for the application to consume */
 static void tcp_recv(struct tsocket *t, struct wolfIP_tcp_seg *seg)
 {
@@ -1573,7 +1589,7 @@ static void tcp_recv(struct tsocket *t, struct wolfIP_tcp_seg *seg)
             /* Buffer full, dropped. This will send a duplicate ack. */
         } else {
             /* Advance ack counter */
-            t->sock.tcp.ack = seq + seg_len;
+            t->sock.tcp.ack = tcp_seq_inc(seq, seg_len);
             timer_binheap_cancel(&t->S->timers, t->sock.tcp.tmr_rto);
             t->sock.tcp.tmr_rto = NO_TIMER;
             t->events |= CB_EVENT_READABLE;
@@ -1742,7 +1758,8 @@ static int ip_output_add_header(struct tsocket *t, struct wolfIP_ip_packet *ip,
     ip->flags_fo = 0;
     ip->ttl = 64;
     ip->proto = proto;
-    ip->id = ee16(t->S->ipcounter++);
+    ip->id = ee16(t->S->ipcounter);
+    t->S->ipcounter = (uint16_t)(t->S->ipcounter + 1);
     ip->csum = 0;
     iphdr_set_checksum(ip);
 
@@ -1815,11 +1832,14 @@ static int tcp_process_ts(struct tsocket *t, const struct wolfIP_tcp_seg *tcp,
                 t->sock.tcp.last_ts = ts->val;
                 if (ts->ecr == 0)
                     return -1; /* No echoed timestamp; fall back to coarse RTT. */
+                if (ee32(ts->ecr) > t->S->last_tick)
+                    return -1; /* Echoed timestamp in the future; ignore. */
                 if (t->sock.tcp.rtt == 0)
                     t->sock.tcp.rtt = (uint32_t)(t->S->last_tick - ee32(ts->ecr));
                 else {
-                    t->sock.tcp.rtt = (uint32_t)(7 * (t->sock.tcp.rtt << 3)) +
-                        ((t->S->last_tick - ee32(ts->ecr)) << 3);
+                    uint64_t rtt_scaled = (uint64_t)t->sock.tcp.rtt << 3;
+                    uint64_t sample_scaled = (t->S->last_tick - ee32(ts->ecr)) << 3;
+                    t->sock.tcp.rtt = (uint32_t)(7 * rtt_scaled + sample_scaled);
                 }
                 return 0;
             } else {
@@ -1830,14 +1850,6 @@ static int tcp_process_ts(struct tsocket *t, const struct wolfIP_tcp_seg *tcp,
     return -1;
 }
 
-/* Increment a TCP sequence number (wraps at 2^32) */
-static inline uint32_t tcp_seq_inc(uint32_t seq, uint32_t n)
-{
-    if (n > UINT32_MAX - seq)
-        return n - (UINT32_MAX - seq) - 1;
-    return seq + n;
-}
-
 #define SEQ_DIFF(a,b) ((a - b) > 0x7FFFFFFF) ? (b - a) : (a - b)
 
 /* Return true if a <= b
@@ -1845,7 +1857,10 @@ static inline uint32_t tcp_seq_inc(uint32_t seq, uint32_t n)
  */
 static inline int tcp_seq_leq(uint32_t a, uint32_t b)
 {
-    return ((int32_t)a - (int32_t)b) <= 0;
+    if (a <= b)
+        return (b - a) <= 0x80000000U;
+    else
+        return (a - b) >= 0x80000000U;
 }
 
 /* Receive an ack */
@@ -1886,7 +1901,11 @@ static void tcp_ack(struct tsocket *t, const struct wolfIP_tcp_seg *tcp)
     if (t->sock.tcp.snd_una != ack &&
             tcp_seq_leq(t->sock.tcp.snd_una, ack) &&
             tcp_seq_leq(ack, t->sock.tcp.seq)) {
-        uint32_t delta = ack - t->sock.tcp.snd_una;
+        uint32_t delta;
+        if (ack >= t->sock.tcp.snd_una)
+            delta = ack - t->sock.tcp.snd_una;
+        else
+            delta = ack + (UINT32_MAX - t->sock.tcp.snd_una) + 1;
         if (delta >= t->sock.tcp.bytes_in_flight)
             t->sock.tcp.bytes_in_flight = 0;
         else
@@ -1909,11 +1928,14 @@ static void tcp_ack(struct tsocket *t, const struct wolfIP_tcp_seg *tcp)
             /* Update rtt */
             if (tcp_process_ts(t, seg, fresh_desc->len) < 0) {
                 /* No timestamp option, use coarse RTT estimation */
-                int rtt = t->S->last_tick - fresh_desc->time_sent;
-                if (t->sock.tcp.rtt == 0) {
-                    t->sock.tcp.rtt = rtt;
-                } else {
-                    t->sock.tcp.rtt = (7 * (t->sock.tcp.rtt << 3)) + (rtt << 3);
+                if (t->S->last_tick >= fresh_desc->time_sent) {
+                    uint32_t rtt = (uint32_t)(t->S->last_tick - fresh_desc->time_sent);
+                    if (t->sock.tcp.rtt == 0) {
+                        t->sock.tcp.rtt = rtt;
+                    } else {
+                        uint64_t rtt_scaled = (uint64_t)t->sock.tcp.rtt << 3;
+                        t->sock.tcp.rtt = (uint32_t)(7 * rtt_scaled + ((uint64_t)rtt << 3));
+                    }
                 }
             }
             /* Update cwnd only if we were cwnd-limited. */
@@ -3101,7 +3123,7 @@ static void icmp_input(struct wolfIP *s, unsigned int if_idx, struct wolfIP_ip_p
         tmp = ip->src;
         ip->src = ip->dst;
         ip->dst = tmp;
-        ip->id = ee16(s->ipcounter++);
+        ip->id = ipcounter_next(s);
         ip->csum = 0;
         iphdr_set_checksum(ip);
         eth_output_add_header(s, if_idx, ip->eth.src, &ip->eth, ETH_TYPE_IP);