Index: uspace/lib/drv/include/usbdiag_iface.h
===================================================================
--- uspace/lib/drv/include/usbdiag_iface.h	(revision 64ce0c1435496748632f7682b2657fdc79aad634)
+++ uspace/lib/drv/include/usbdiag_iface.h	(revision 98b1d301e61446aa87b9e47da002832a97df3f07)
@@ -65,11 +65,11 @@
 void usbdiag_disconnect(async_sess_t*);
 
-int usbdiag_test_in(async_exch_t*, const usbdiag_test_params_t *, usbdiag_test_results_t *);
-int usbdiag_test_out(async_exch_t*, const usbdiag_test_params_t *, usbdiag_test_results_t *);
+errno_t usbdiag_test_in(async_exch_t*, const usbdiag_test_params_t *, usbdiag_test_results_t *);
+errno_t usbdiag_test_out(async_exch_t*, const usbdiag_test_params_t *, usbdiag_test_results_t *);
 
 /** USB diagnostic device communication interface. */
 typedef struct {
-	int (*test_in)(ddf_fun_t*, const usbdiag_test_params_t *, usbdiag_test_results_t *);
-	int (*test_out)(ddf_fun_t*, const usbdiag_test_params_t *, usbdiag_test_results_t *);
+	errno_t (*test_in)(ddf_fun_t*, const usbdiag_test_params_t *, usbdiag_test_results_t *);
+	errno_t (*test_out)(ddf_fun_t*, const usbdiag_test_params_t *, usbdiag_test_results_t *);
 } usbdiag_iface_t;