diff --git a/sys/net/if.c b/sys/net/if.c
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -359,7 +359,8 @@
 	ifp = ifnet_byindex(idx);
 	if (ifp == NULL || (ifp->if_flags & IFF_DYING))
 		return (NULL);
-	if_ref(ifp);
+	if (!if_try_ref(ifp))
+		return (NULL);
 	return (ifp);
 }
 
@@ -738,9 +739,18 @@
 void
 if_ref(struct ifnet *ifp)
 {
+	u_int old;
 
 	/* We don't assert the ifnet list lock here, but arguably should. */
-	refcount_acquire(&ifp->if_refcount);
+	old = refcount_acquire(&ifp->if_refcount);
+	KASSERT(old > 0, ("%s: ifp %p has 0 refs", __func__, ifp));
+}
+
+bool
+if_try_ref(struct ifnet *ifp)
+{
+	NET_EPOCH_ASSERT();
+	return (refcount_acquire_if_not_zero(&ifp->if_refcount));
 }
 
 void
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -661,6 +661,7 @@
 int	if_printf(struct ifnet *, const char *, ...) __printflike(2, 3);
 void	if_ref(struct ifnet *);
 void	if_rele(struct ifnet *);
+bool	if_try_ref(struct ifnet *);
 int	if_setlladdr(struct ifnet *, const u_char *, int);
 int	if_tunnel_check_nesting(struct ifnet *, struct mbuf *, uint32_t, int);
 void	if_up(struct ifnet *);