diff --git a/sys/net/ip_mroute/ip_mroute.c b/sys/net/ip_mroute/ip_mroute.c
--- a/sys/net/ip_mroute/ip_mroute.c
+++ b/sys/net/ip_mroute/ip_mroute.c
@@ -87,12 +87,12 @@
     "Multicast Routing Statistics (struct mrtstat, netinet/ip_mroute.h)");
 
 static struct mfc	*mfctable[MFCTBLSIZ];
-SYSCTL_OPAQUE(_net_inet_ip, OID_AUTO, mfctable, CTLFLAG_RD,
+SYSCTL_OPAQUE(_net_inet_ip, OID_AUTO, mfctable, CTLFLAG_RD|CTLFLAG_NOLOCK,
     &mfctable, sizeof(mfctable), "S,*mfc[MFCTBLSIZ]",
     "Multicast Forwarding Table (struct *mfc[MFCTBLSIZ], netinet/ip_mroute.h)");
 
 static struct vif	viftable[MAXVIFS];
-SYSCTL_OPAQUE(_net_inet_ip, OID_AUTO, viftable, CTLFLAG_RD,
+SYSCTL_OPAQUE(_net_inet_ip, OID_AUTO, viftable, CTLFLAG_RD|CTLFLAG_NOLOCK,
     &viftable, sizeof(viftable), "S,vif[MAXVIFS]",
     "Multicast Virtual Interfaces (struct vif[MAXVIFS], netinet/ip_mroute.h)");