Index: uspace/app/tmon/list.c
===================================================================
--- uspace/app/tmon/list.c	(revision be01eb379a65399d13f7e4a0b6b5a403268d76dc)
+++ uspace/app/tmon/list.c	(revision 98b1d301e61446aa87b9e47da002832a97df3f07)
@@ -49,5 +49,5 @@
 static void print_list_item(service_id_t svc)
 {
-	int rc;
+	errno_t rc;
 	devman_handle_t diag_handle = 0;
 
Index: uspace/app/tmon/resolve.h
===================================================================
--- uspace/app/tmon/resolve.h	(revision be01eb379a65399d13f7e4a0b6b5a403268d76dc)
+++ uspace/app/tmon/resolve.h	(revision 98b1d301e61446aa87b9e47da002832a97df3f07)
@@ -39,6 +39,6 @@
 #include <devman.h>
 
-int tmon_resolve_default(devman_handle_t *);
-int tmon_resolve_named(const char *, devman_handle_t *);
+errno_t tmon_resolve_default(devman_handle_t *);
+errno_t tmon_resolve_named(const char *, devman_handle_t *);
 
 #endif /* TMON_RESOLVE_H_ */
Index: uspace/app/tmon/tests.c
===================================================================
--- uspace/app/tmon/tests.c	(revision be01eb379a65399d13f7e4a0b6b5a403268d76dc)
+++ uspace/app/tmon/tests.c	(revision 98b1d301e61446aa87b9e47da002832a97df3f07)
@@ -66,7 +66,7 @@
  * @return EOK if successful (in such case caller becomes the owner of `params`).
  */
-static int read_params(int argc, char *argv[], void **params)
-{
-	int rc;
+static errno_t read_params(int argc, char *argv[], void **params)
+{
+	errno_t rc;
 	usbdiag_test_params_t *p = (usbdiag_test_params_t *) malloc(sizeof(usbdiag_test_params_t));
 	if (!p)
@@ -182,5 +182,5 @@
 
 	usbdiag_test_results_t results;
-	int rc = usbdiag_test_in(exch, params, &results);
+	errno_t rc = usbdiag_test_in(exch, params, &results);
 	if (rc != EOK) {
 		puts("failed\n");
@@ -207,5 +207,5 @@
 
 	usbdiag_test_results_t results;
-	int rc = usbdiag_test_out(exch, params, &results);
+	errno_t rc = usbdiag_test_out(exch, params, &results);
 	if (rc) {
 		puts("failed\n");
Index: uspace/app/tmon/tf.c
===================================================================
--- uspace/app/tmon/tf.c	(revision be01eb379a65399d13f7e4a0b6b5a403268d76dc)
+++ uspace/app/tmon/tf.c	(revision 98b1d301e61446aa87b9e47da002832a97df3f07)
@@ -67,5 +67,6 @@
 	}
 
-	int rc, ec;
+	errno_t rc;
+	int ec;
 	char path[MAX_PATH_LENGTH];
 	if ((rc = devman_fun_get_path(fun, path, sizeof(path)))) {
Index: uspace/app/tmon/tf.h
===================================================================
--- uspace/app/tmon/tf.h	(revision be01eb379a65399d13f7e4a0b6b5a403268d76dc)
+++ uspace/app/tmon/tf.h	(revision 98b1d301e61446aa87b9e47da002832a97df3f07)
@@ -42,7 +42,7 @@
 /** Operations to implement by all tests. */
 typedef struct tmon_test_ops {
-	int (*pre_run)(void *);
-	int (*run)(async_exch_t *, const void *);
-	int (*read_params)(int, char **, void **);
+	errno_t (*pre_run)(void *);
+	errno_t (*run)(async_exch_t *, const void *);
+	errno_t (*read_params)(int, char **, void **);
 } tmon_test_ops_t;