diff -r 7e6d48a89a03 sys/dev/cxgbe/t4_netmap.c
--- a/sys/dev/cxgbe/t4_netmap.c	Mon Dec 05 19:20:08 2016 -0800
+++ b/sys/dev/cxgbe/t4_netmap.c	Tue Dec 06 07:23:26 2016 -0800
@@ -870,7 +870,8 @@ cxgbe_nm_attach(struct vi_info *vi)
 	na.nm_register = cxgbe_netmap_reg;
 	na.num_tx_rings = vi->nnmtxq;
 	na.num_rx_rings = vi->nnmrxq;
-	netmap_attach(&na);	/* This adds IFCAP_NETMAP to if_capabilities */
+	if (netmap_attach(&na) == 0)	/* This used to add IFCAP_NETMAP to if_capabilities */
+		vi->ifp->if_capabilities |= IFCAP_NETMAP;
 }
 
 void