diff --git a/sys/dev/netif/oce/oce_mbox.c b/sys/dev/netif/oce/oce_mbox.c
index 1111111..2222222 100644
--- a/sys/dev/netif/oce/oce_mbox.c
+++ b/sys/dev/netif/oce/oce_mbox.c
@@ -445,6 +445,8 @@
 
 	/* copy the mac addres in the output parameter */
 	mac->size_of_struct = fwcmd->params.rsp.mac.size_of_struct;
+	if (mac->size_of_struct > sizeof(mac->mac_addr))
+		mac->size_of_struct = sizeof(mac->mac_addr);
 	bcopy(&fwcmd->params.rsp.mac.mac_addr[0], &mac->mac_addr[0],
 		mac->size_of_struct);
 error: