diff --git a/bsp/lm3s8962/rtconfig.h b/bsp/lm3s8962/rtconfig.h
index c4158624d4..08ea77ab04 100644
--- a/bsp/lm3s8962/rtconfig.h
+++ b/bsp/lm3s8962/rtconfig.h
@@ -150,4 +150,8 @@
 #define RT_LWIP_ETHTHREAD_PRIORITY		23
 #define RT_LWIP_ETHTHREAD_MBOX_SIZE		4
 #define RT_LWIP_ETHTHREAD_STACKSIZE		512
+
+/* the size of each pbuf in the pbuf pool. */
+#define RT_LWIP_PBUF_POOL_BUFSIZE		1500
+
 #endif
diff --git a/bsp/lm3s9b9x/rtconfig.h b/bsp/lm3s9b9x/rtconfig.h
index a0835068c7..644aaefdc1 100644
--- a/bsp/lm3s9b9x/rtconfig.h
+++ b/bsp/lm3s9b9x/rtconfig.h
@@ -154,5 +154,7 @@
 /* TCP receive window. */
 #define RT_LWIP_TCP_WND		8192
 
+/* the size of each pbuf in the pbuf pool. */
+#define RT_LWIP_PBUF_POOL_BUFSIZE	1500
 
 #endif