Index: sys/netinet/tcp_hostcache.h
===================================================================
--- sys/netinet/tcp_hostcache.h
+++ sys/netinet/tcp_hostcache.h
@@ -55,7 +55,7 @@
 	/* endpoint specific values for tcp */
 	uint32_t	rmx_mtu;	/* MTU for this path */
 	uint32_t	rmx_ssthresh;	/* outbound gateway buffer limit */
-	u_long		rmx_rtt;	/* estimated round trip time */
+	uint32_t	rmx_rtt;	/* estimated round trip time */
 	u_long		rmx_rttvar;	/* estimated rtt variance */
 	u_long		rmx_cwnd;	/* congestion window */
 	u_long		rmx_sendpipe;	/* outbound delay-bandwidth product */
Index: sys/netinet/tcp_hostcache.c
===================================================================
--- sys/netinet/tcp_hostcache.c
+++ sys/netinet/tcp_hostcache.c
@@ -534,8 +534,8 @@
 		if (hc_entry->rmx_rtt == 0)
 			hc_entry->rmx_rtt = hcml->rmx_rtt;
 		else
-			hc_entry->rmx_rtt =
-			    (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
+			hc_entry->rmx_rtt = ((uint64_t)hc_entry->rmx_rtt +
+			    (uint64_t)hcml->rmx_rtt) / 2;
 		TCPSTAT_INC(tcps_cachedrtt);
 	}
 	if (hcml->rmx_rttvar != 0) {
@@ -622,7 +622,7 @@
 #endif
 			    hc_entry->rmx_mtu,
 			    hc_entry->rmx_ssthresh,
-			    msec(hc_entry->rmx_rtt *
+			    msec((u_long)hc_entry->rmx_rtt *
 				(RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
 			    msec(hc_entry->rmx_rttvar *
 				(RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
Index: sys/netinet/tcp_var.h
===================================================================
--- sys/netinet/tcp_var.h
+++ sys/netinet/tcp_var.h
@@ -404,7 +404,7 @@
 struct hc_metrics_lite {	/* must stay in sync with hc_metrics */
 	uint32_t	rmx_mtu;	/* MTU for this path */
 	uint32_t	rmx_ssthresh;	/* outbound gateway buffer limit */
-	u_long		rmx_rtt;	/* estimated round trip time */
+	uint32_t	rmx_rtt;	/* estimated round trip time */
 	u_long		rmx_rttvar;	/* estimated rtt variance */
 	u_long		rmx_cwnd;	/* congestion window */
 	u_long		rmx_sendpipe;   /* outbound delay-bandwidth product */