diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 01870bd..dcb19f5 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -704,7 +704,7 @@
 			 * Make sure that we have exactly size bytes
 			 * available to the caller, no more, no less.
 			 */
-			skb->avail_size = size;
+			skb->reserved_tailroom = skb->end - skb->tail - size;
 			return skb;
 		}
 		__kfree_skb(skb);