Index: uspace/lib/usbdev/src/pipes.c
===================================================================
--- uspace/lib/usbdev/src/pipes.c	(revision 317a4637d99500a6600c65568a00f718c274a6ea)
+++ uspace/lib/usbdev/src/pipes.c	(revision 56bdd9a4306c6d99a59c72a07fe62501b10576c1)
@@ -54,16 +54,15 @@
 static usb_address_t get_my_address(async_sess_t *sess, const ddf_dev_t *dev)
 {
+	assert(sess);
 	async_exch_t *exch = async_exchange_begin(sess);
-	
-	sysarg_t address;
-	int rc = async_req_1_1(exch, DEV_IFACE_ID(USB_DEV_IFACE),
-	    IPC_M_USB_GET_MY_ADDRESS, &address);
-	
+	if (!exch)
+		return ENOMEM;
+
+	usb_address_t address;
+	const int ret = usb_get_my_address(exch, &address);
+
 	async_exchange_end(exch);
-	
-	if (rc != EOK)
-		return rc;
-	
-	return (usb_address_t) address;
+
+	return (ret == EOK) ? address : ret;
 }
 
@@ -71,5 +70,5 @@
  *
  * @param device Device in question.
- * @return Interface number (negative code means any).
+ * @return Error code (ENOTSUP means any).
  */
 int usb_device_get_assigned_interface(const ddf_dev_t *device)
@@ -80,19 +79,16 @@
 	    IPC_FLAG_BLOCKING);
 	if (!parent_sess)
-		return -1;
-	
+		return ENOMEM;
+
 	async_exch_t *exch = async_exchange_begin(parent_sess);
-	
-	sysarg_t iface_no;
-	int rc = async_req_1_1(exch, DEV_IFACE_ID(USB_DEV_IFACE),
-	    IPC_M_USB_GET_MY_INTERFACE, &iface_no);
-	
-	async_exchange_end(exch);
-	async_hangup(parent_sess);
-	
-	if (rc != EOK)
-		return -1;
-	
-	return (int) iface_no;
+	if (!exch) {
+		async_hangup(parent_sess);
+		return ENOMEM;
+	}
+
+	int iface_no;
+	const int ret = usb_get_my_interface(exch, &iface_no);
+
+	return ret == EOK ? iface_no : ret;
 }