Index: uspace/lib/hound/include/hound/server.h
===================================================================
--- uspace/lib/hound/include/hound/server.h	(revision 984a9ba2fa05c490a7066737655ed19130c714e8)
+++ uspace/lib/hound/include/hound/server.h	(revision be0f5e4d59071204ff8b374bbff33ba65da0d3e1)
@@ -40,10 +40,11 @@
 #include <loc.h>
 
-typedef void (*dev_change_callback_t)(void);
+typedef void (*dev_change_callback_t)(void *);
 typedef errno_t (*device_callback_t)(service_id_t, const char *);
 
 errno_t hound_server_register(const char *name, service_id_t *id);
 void hound_server_unregister(service_id_t id);
-errno_t hound_server_set_device_change_callback(dev_change_callback_t cb);
+errno_t hound_server_set_device_change_callback(dev_change_callback_t cb,
+    void *);
 errno_t hound_server_devices_iterate(device_callback_t callback);
 
Index: uspace/lib/hound/src/protocol.c
===================================================================
--- uspace/lib/hound/src/protocol.c	(revision 984a9ba2fa05c490a7066737655ed19130c714e8)
+++ uspace/lib/hound/src/protocol.c	(revision be0f5e4d59071204ff8b374bbff33ba65da0d3e1)
@@ -750,7 +750,8 @@
  * @return Error code.
  */
-errno_t hound_server_set_device_change_callback(dev_change_callback_t cb)
-{
-	return loc_register_cat_change_cb(cb);
+errno_t hound_server_set_device_change_callback(dev_change_callback_t cb,
+    void *arg)
+{
+	return loc_register_cat_change_cb(cb, arg);
 }