diff --git a/sys/bus/pci/pci_pci.c b/sys/bus/pci/pci_pci.c
--- a/sys/bus/pci/pci_pci.c
+++ b/sys/bus/pci/pci_pci.c
@@ -706,6 +706,8 @@
 		return (0);
 	case 0x84cb8086:
 		switch (slot) {
+		default:
+			return (0);
 		case 0x12:
 			/* Intel 82454NX PXB#0, Bus#A */
 			*busnum = read_config(bus, 0x10, func, 0xd0, 1);