diff --git a/mongoose.c b/mongoose.c
index d0bb9e85..74d75b78 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -15308,6 +15308,10 @@ static err_t mg_lwip_accept_cb(void *arg, struct tcp_pcb *newtpcb, err_t err) {
   struct mg_connection *lc = (struct mg_connection *) arg, *nc;
   struct mg_lwip_conn_state *lcs, *cs;
   struct tcp_pcb_listen *lpcb;
+  if (newtpcb == NULL) {
+    LOG(LL_ERROR, ("%p accept error %d", lc, (int) err));
+    return ERR_ABRT;
+  }
   LOG(LL_DEBUG,
       ("%p conn %p from %s:%u", lc, newtpcb,
        IPADDR_NTOA(ipX_2_ip(&newtpcb->remote_ip)), newtpcb->remote_port));
diff --git a/src/common/platforms/lwip/mg_lwip_net_if.c b/src/common/platforms/lwip/mg_lwip_net_if.c
index 66c5f8f2..b9e2e067 100644
--- a/src/common/platforms/lwip/mg_lwip_net_if.c
+++ b/src/common/platforms/lwip/mg_lwip_net_if.c
@@ -383,6 +383,10 @@ static err_t mg_lwip_accept_cb(void *arg, struct tcp_pcb *newtpcb, err_t err) {
   struct mg_connection *lc = (struct mg_connection *) arg, *nc;
   struct mg_lwip_conn_state *lcs, *cs;
   struct tcp_pcb_listen *lpcb;
+  if (newtpcb == NULL) {
+    LOG(LL_ERROR, ("%p accept error %d", lc, (int) err));
+    return ERR_ABRT;
+  }
   LOG(LL_DEBUG,
       ("%p conn %p from %s:%u", lc, newtpcb,
        IPADDR_NTOA(ipX_2_ip(&newtpcb->remote_ip)), newtpcb->remote_port));