Index: if_vtnet.c
===================================================================
--- if_vtnet.c	(revision 299234)
+++ if_vtnet.c	(working copy)
@@ -323,11 +323,13 @@
 		break;
 	case MOD_QUIESCE:
 	case MOD_UNLOAD:
-		if (uma_zone_get_cur(vtnet_tx_header_zone) > 0)
-			error = EBUSY;
-		else if (type == MOD_UNLOAD) {
-			uma_zdestroy(vtnet_tx_header_zone);
-			vtnet_tx_header_zone = NULL;
+                if (vtnet_tx_header_zone) {
+			if (uma_zone_get_cur(vtnet_tx_header_zone) > 0)
+				error = EBUSY;
+			else if (type == MOD_UNLOAD) {
+				uma_zdestroy(vtnet_tx_header_zone);
+				vtnet_tx_header_zone = NULL;
+			}
 		}
 		break;
 	case MOD_SHUTDOWN: