Index: uspace/app/vuhid/device.c
===================================================================
--- uspace/app/vuhid/device.c	(revision 97663ee3dcc54972dc8cf54f071e1f100adf3400)
+++ uspace/app/vuhid/device.c	(revision d197496661fecf853a30e11375ef0530df933cff)
@@ -60,5 +60,5 @@
 static int on_data_to_device(usbvirt_device_t *dev,
     usb_endpoint_t ep, usb_transfer_type_t tr_type,
-    void *data, size_t data_size)
+    const void *data, size_t data_size)
 {
 	vuhid_data_t *vuhid = dev->device_data;
Index: uspace/app/vuhid/hids/bootkbd.c
===================================================================
--- uspace/app/vuhid/hids/bootkbd.c	(revision 97663ee3dcc54972dc8cf54f071e1f100adf3400)
+++ uspace/app/vuhid/hids/bootkbd.c	(revision d197496661fecf853a30e11375ef0530df933cff)
@@ -102,5 +102,5 @@
 
 static int on_data_out(vuhid_interface_t *iface,
-    void *buffer, size_t buffer_size)
+    const void *buffer, size_t buffer_size)
 {
 	if (buffer_size == 0) {
Index: uspace/app/vuhid/virthid.h
===================================================================
--- uspace/app/vuhid/virthid.h	(revision 97663ee3dcc54972dc8cf54f071e1f100adf3400)
+++ uspace/app/vuhid/virthid.h	(revision d197496661fecf853a30e11375ef0530df933cff)
@@ -71,5 +71,5 @@
 
 	int (*on_data_in)(vuhid_interface_t *, void *, size_t, size_t *);
-	int (*on_data_out)(vuhid_interface_t *, void *, size_t);
+	int (*on_data_out)(vuhid_interface_t *, const void *, size_t);
 	void (*live)(vuhid_interface_t *);
 
Index: uspace/lib/usbvirt/include/usbvirt/device.h
===================================================================
--- uspace/lib/usbvirt/include/usbvirt/device.h	(revision 97663ee3dcc54972dc8cf54f071e1f100adf3400)
+++ uspace/lib/usbvirt/include/usbvirt/device.h	(revision d197496661fecf853a30e11375ef0530df933cff)
@@ -57,5 +57,5 @@
 typedef int (*usbvirt_on_data_to_device_t)(usbvirt_device_t *dev,
     usb_endpoint_t endpoint, usb_transfer_type_t transfer_type,
-    void *buffer, size_t buffer_size);
+    const void *buffer, size_t buffer_size);
 
 /** Callback for data from device (IN transaction).
@@ -208,8 +208,8 @@
     uint8_t *, size_t *, const void *, size_t);
 
-int usbvirt_control_write(usbvirt_device_t *, void *, size_t, void *, size_t);
-int usbvirt_control_read(usbvirt_device_t *, void *, size_t, void *, size_t, size_t *);
+int usbvirt_control_write(usbvirt_device_t *, const void *, size_t, void *, size_t);
+int usbvirt_control_read(usbvirt_device_t *, const void *, size_t, void *, size_t, size_t *);
 int usbvirt_data_out(usbvirt_device_t *, usb_transfer_type_t, usb_endpoint_t,
-    void *, size_t);
+    const void *, size_t);
 int usbvirt_data_in(usbvirt_device_t *, usb_transfer_type_t, usb_endpoint_t,
     void *, size_t, size_t *);
Index: uspace/lib/usbvirt/src/ctrltransfer.c
===================================================================
--- uspace/lib/usbvirt/src/ctrltransfer.c	(revision 97663ee3dcc54972dc8cf54f071e1f100adf3400)
+++ uspace/lib/usbvirt/src/ctrltransfer.c	(revision d197496661fecf853a30e11375ef0530df933cff)
@@ -51,5 +51,5 @@
 int process_control_transfer(usbvirt_device_t *dev,
     usbvirt_control_request_handler_t *control_handlers,
-    usb_device_request_setup_packet_t *setup,
+    const usb_device_request_setup_packet_t *setup,
     uint8_t *data, size_t *data_sent_size)
 {
Index: uspace/lib/usbvirt/src/private.h
===================================================================
--- uspace/lib/usbvirt/src/private.h	(revision 97663ee3dcc54972dc8cf54f071e1f100adf3400)
+++ uspace/lib/usbvirt/src/private.h	(revision d197496661fecf853a30e11375ef0530df933cff)
@@ -40,5 +40,5 @@
 int process_control_transfer(usbvirt_device_t *,
     usbvirt_control_request_handler_t *,
-    usb_device_request_setup_packet_t *,
+    const usb_device_request_setup_packet_t *,
     uint8_t *, size_t *);
 
Index: uspace/lib/usbvirt/src/transfer.c
===================================================================
--- uspace/lib/usbvirt/src/transfer.c	(revision 97663ee3dcc54972dc8cf54f071e1f100adf3400)
+++ uspace/lib/usbvirt/src/transfer.c	(revision d197496661fecf853a30e11375ef0530df933cff)
@@ -51,5 +51,5 @@
  */
 static int usbvirt_control_transfer(usbvirt_device_t *dev,
-    void *setup, size_t setup_size,
+    const void *setup, size_t setup_size,
     void *data, size_t data_size, size_t *data_size_sent)
 {
@@ -60,5 +60,5 @@
 		return ESTALL;
 	}
-	usb_device_request_setup_packet_t *setup_packet = setup;
+	const usb_device_request_setup_packet_t *setup_packet = setup;
 	if (data_size != setup_packet->length) {
 		return ESTALL;
@@ -100,6 +100,6 @@
  * @return Error code.
  */
-int usbvirt_control_write(usbvirt_device_t *dev, void *setup, size_t setup_size,
-    void *data, size_t data_size)
+int usbvirt_control_write(usbvirt_device_t *dev, const void *setup,
+    size_t setup_size, void *data, size_t data_size)
 {
 	return usbvirt_control_transfer(dev, setup, setup_size,
@@ -119,5 +119,5 @@
  * @return Error code.
  */
-int usbvirt_control_read(usbvirt_device_t *dev, void *setup, size_t setup_size,
+int usbvirt_control_read(usbvirt_device_t *dev, const void *setup, size_t setup_size,
     void *data, size_t data_size, size_t *data_size_sent)
 {
@@ -136,5 +136,5 @@
  */
 int usbvirt_data_out(usbvirt_device_t *dev, usb_transfer_type_t transf_type,
-    usb_endpoint_t endpoint, void *data, size_t data_size)
+    usb_endpoint_t endpoint, const void *data, size_t data_size)
 {
 	if ((endpoint <= 0) || (endpoint >= USBVIRT_ENDPOINT_MAX)) {