Index: head/sys/netinet/cc/cc_cubic.c
===================================================================
--- head/sys/netinet/cc/cc_cubic.c
+++ head/sys/netinet/cc/cc_cubic.c
@@ -185,12 +185,11 @@
 				 */
 				if (CCV(ccv, snd_cwnd) < w_tf)
 					CCV(ccv, snd_cwnd) = ulmin(w_tf, INT_MAX);
-			}
-
-			else if (CCV(ccv, snd_cwnd) < w_cubic_next) {
+			} else if (CCV(ccv, snd_cwnd) < w_cubic_next) {
 				/*
 				 * Concave or convex region, follow CUBIC
 				 * cwnd growth.
+				 * Only update snd_cwnd, if it doesn't shrink.
 				 */
 				if (V_tcp_do_rfc3465)
 					CCV(ccv, snd_cwnd) = ulmin(w_cubic_next,