diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index dac7676..f69a185 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1058,11 +1058,11 @@
 		goto alloc_fail;
 	}
 
-	ctrlsize = le16_to_cpu(epctrl->wMaxPacketSize);
-	readsize = le16_to_cpu(epread->wMaxPacketSize) *
+	ctrlsize = usb_endpoint_maxp(epctrl);
+	readsize = usb_endpoint_maxp(epread) *
 				(quirks == SINGLE_RX_URB ? 1 : 2);
 	acm->combined_interfaces = combined_interfaces;
-	acm->writesize = le16_to_cpu(epwrite->wMaxPacketSize) * 20;
+	acm->writesize = usb_endpoint_maxp(epwrite) * 20;
 	acm->control = control_interface;
 	acm->data = data_interface;
 	acm->minor = minor;