diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index d200e7c3..23fbbbba 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -375,7 +375,7 @@ err_t lwip_tcp_event(void *arg, struct tcp_pcb *pcb,
 #define TCP_EVENT_RECV(pcb,p,err,ret) \
                         if((pcb)->recv != NULL) \
                         { ret = (pcb)->recv((pcb)->callback_arg,(pcb),(p),(err)); } else { \
-            pbuf_free(p); }
+                          if (p) pbuf_free(p); }
 #define TCP_EVENT_CONNECTED(pcb,err,ret) \
                         if((pcb)->connected != NULL) \
                         (ret = (pcb)->connected((pcb)->callback_arg,(pcb),(err)))