diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index dc15113..688b955 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1607,6 +1607,9 @@
 		 */
 		if (window <= free_space - mss || window > free_space)
 			window = (free_space/mss)*mss;
+		else if (mss == full_space &&
+		         free_space > window + full_space/2)
+			window = free_space;
 	}
 
 	return window;