diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index f998761abc..3f002252ac 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -403,7 +403,7 @@ static void vfio_probe_ati_bar4_quirk(VFIOPCIDevice *vdev, int nr)
 
     /* This windows doesn't seem to be used except by legacy VGA code */
     if (!vfio_pci_is(vdev, PCI_VENDOR_ID_ATI, PCI_ANY_ID) ||
-        !vdev->vga || nr != 4) {
+        !vdev->vga || nr != 4 || !vdev->bars[4].ioport) {
         return;
     }