diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 567ffb159d..e0ca69044a 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -2746,8 +2746,10 @@ static void xhci_doorbell_write(void *ptr, target_phys_addr_t reg,
 
 static const MemoryRegionOps xhci_cap_ops = {
     .read = xhci_cap_read,
-    .valid.min_access_size = 4,
+    .valid.min_access_size = 1,
     .valid.max_access_size = 4,
+    .impl.min_access_size = 4,
+    .impl.max_access_size = 4,
     .endianness = DEVICE_LITTLE_ENDIAN,
 };