diff --git a/src/machine/m_at_socket7_s7.c b/src/machine/m_at_socket7_s7.c
index 685dcb7a5..3e0bfd703 100644
--- a/src/machine/m_at_socket7_s7.c
+++ b/src/machine/m_at_socket7_s7.c
@@ -540,7 +540,7 @@ machine_at_txp4_init(const machine_t *model)
     pci_register_slot(0x0B, PCI_CARD_NORMAL, 2, 3, 4, 1);
     pci_register_slot(0x0A, PCI_CARD_NORMAL, 3, 4, 1, 2);
     pci_register_slot(0x09, PCI_CARD_NORMAL, 4, 1, 2, 3);
-    pci_register_slot(0x07, PCI_CARD_SOUTHBRIDGE, 1, 2, 3, 4);	/* PIIX4 */
+    pci_register_slot(0x01, PCI_CARD_SOUTHBRIDGE, 1, 2, 3, 4);	/* PIIX4 */
     pci_register_slot(0x0D, PCI_CARD_NORMAL, 1, 2, 3, 4);
     pci_register_slot(0x08, PCI_CARD_NORMAL, 1, 2, 3, 4);
     device_add(&i430tx_device);