Index: sys/dev/fxp/if_fxp.c
===================================================================
--- sys/dev/fxp/if_fxp.c	(revision 218497)
+++ sys/dev/fxp/if_fxp.c	(working copy)
@@ -2823,8 +2823,10 @@
 
 	case SIOCADDMULTI:
 	case SIOCDELMULTI:
+		FXP_LOCK(sc);
 		if ((ifp->if_drv_flags & IFF_DRV_RUNNING) != 0)
-			fxp_init(sc);
+			fxp_init_body(sc, 0);
+		FXP_UNLOCK(sc);
 		break;
 
 	case SIOCSIFMEDIA: