diff --git a/src/core/pbuf.c b/src/core/pbuf.c
index 1442f243..c176adbe 100644
--- a/src/core/pbuf.c
+++ b/src/core/pbuf.c
@@ -307,7 +307,8 @@ pbuf_realloc(struct pbuf *p, u16_t new_len)
   /* (other types merely adjust their length fields */
   if ((q->type == PBUF_RAM) && (rem_len != q->len)) {
     /* reallocate and adjust the length of the pbuf that will be split */
-    mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rem_len);
+    q = mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rem_len);
+    LWIP_ASSERT("mem_realloc give q == NULL", q != NULL);
   }
   /* adjust length fields for new last pbuf */
   q->len = rem_len;