diff --git a/VERSION b/VERSION
index 400aed76..cb821f2f 100644
--- a/VERSION
+++ b/VERSION
@@ -13,7 +13,7 @@ gwen:
 gitlab:
     espconn:    3a998034
     freertos:   ac047746
-    lwip:       3e8cc2ef
+    lwip:       3c4f800b
     driver:     7bee5263
     mbedtls:    1ac9f1f4
     ssl:        eefb383a
\ No newline at end of file
diff --git a/lib/liblwip.a b/lib/liblwip.a
index 6101b3ef..d595d17c 100644
Binary files a/lib/liblwip.a and b/lib/liblwip.a differ
diff --git a/third_party/lwip/core/tcp_out.c b/third_party/lwip/core/tcp_out.c
index 778976ca..cd02ea70 100644
--- a/third_party/lwip/core/tcp_out.c
+++ b/third_party/lwip/core/tcp_out.c
@@ -464,6 +464,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
     LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) || (pos == len));
 #endif /* TCP_OVERSIZE */
 
+#if !LWIP_NETIF_TX_SINGLE_PBUF
     /*
      * Phase 2: Chain a new pbuf to the end of pcb->unsent.
      *
@@ -513,6 +514,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
       pos += seglen;
       queuelen += pbuf_clen(concat_p);
     }
+#endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
   } else {
 #if TCP_OVERSIZE
     LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",