diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c
index 7092a61c4dc8465fcf17ff71b289cf25bbb8b559..7e538f71f5fbae087c3e3e4367d60e08cd609ac5 100644
--- a/net/ipv4/tcp_dctcp.c
+++ b/net/ipv4/tcp_dctcp.c
@@ -209,7 +209,7 @@ static void dctcp_update_alpha(struct sock *sk, u32 flags)
 
 		/* alpha = (1 - g) * alpha + g * F */
 
-		alpha -= alpha >> dctcp_shift_g;
+		alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g);
 		if (bytes_ecn) {
 			/* If dctcp_shift_g == 1, a 32bit value would overflow
 			 * after 8 Mbytes.