diff --git a/devicemodel/hw/pci/xhci.c b/devicemodel/hw/pci/xhci.c
old mode 100755
new mode 100644
index b09b3cb9a..70f364019
--- a/devicemodel/hw/pci/xhci.c
+++ b/devicemodel/hw/pci/xhci.c
@@ -373,7 +373,7 @@ struct pci_xhci_vdev {
 	struct pci_xhci_dev_emu  **devices; /* XHCI[port] = device */
 	struct pci_xhci_dev_emu  **slots;   /* slots assigned from 1 */
 
-	bool		slot_allocated[XHCI_MAX_SLOTS];
+	bool		slot_allocated[XHCI_MAX_SLOTS + 1];
 	int		ndevices;
 	uint16_t	pid;
 	uint16_t	vid;