diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 1397194..0e807a8 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -212,12 +212,12 @@ void tcp_select_initial_window(int __space, __u32 mss,
 
 	/* If no clamp set the clamp to the max possible scaled window */
 	if (*window_clamp == 0)
-		(*window_clamp) = (65535 << 14);
+		(*window_clamp) = (U16_MAX << TCP_MAX_WSCALE);
 	space = min(*window_clamp, space);
 
 	/* Quantize space offering to a multiple of mss if possible. */
 	if (space > mss)
-		space = (space / mss) * mss;
+		space = rounddown(space, mss);
 
 	/* NOTE: offering an initial window larger than 32767
 	 * will break some buggy TCP stacks. If the admin tells us
@@ -234,13 +234,11 @@ void tcp_select_initial_window(int __space, __u32 mss,
 
 	(*rcv_wscale) = 0;
 	if (wscale_ok) {
-		/* Set window scaling on max possible window
-		 * See RFC1323 for an explanation of the limit to 14
-		 */
+		/* Set window scaling on max possible window */
 		space = max_t(u32, space, sysctl_tcp_rmem[2]);
 		space = max_t(u32, space, sysctl_rmem_max);
 		space = min_t(u32, space, *window_clamp);
-		while (space > 65535 && (*rcv_wscale) < 14) {
+		while (space > U16_MAX && (*rcv_wscale) < TCP_MAX_WSCALE) {
 			space >>= 1;
 			(*rcv_wscale)++;
 		}
@@ -253,7 +251,7 @@ void tcp_select_initial_window(int __space, __u32 mss,
 	}
 
 	/* Set the clamp no higher than max representable value */
-	(*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp);
+	(*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp);
 }
 EXPORT_SYMBOL(tcp_select_initial_window);