Index: uspace/drv/bus/usb/xhci/endpoint.c
===================================================================
--- uspace/drv/bus/usb/xhci/endpoint.c	(revision 774aa33295605fdbbdcdc06516322c0665399f63)
+++ uspace/drv/bus/usb/xhci/endpoint.c	(revision 2fc9bfdff4f7f7961c56c7e4f3521ee05f4582e8)
@@ -102,5 +102,7 @@
 	if (dev->speed >= USB_SPEED_HIGH ||
 	    ep->transfer_type != USB_TRANSFER_INTERRUPT) {
-		xhci_ep->interval = 1 << (xhci_ep->interval - 1);
+
+		if (xhci_ep->interval > 0)
+			xhci_ep->interval = 1 << (xhci_ep->interval - 1);
 	}