Index: uspace/lib/c/include/async.h
===================================================================
--- uspace/lib/c/include/async.h	(revision 9c0242b0b40302f92f8d0ac933b78ff30bf0348d)
+++ uspace/lib/c/include/async.h	(revision ef15fbbac0915e003c970e47614ca22e47e3ed96)
@@ -53,5 +53,16 @@
 typedef void (*async_client_data_dtor_t)(void *);
 
-typedef void (*async_client_conn_t)(ipc_callid_t, ipc_call_t *);
+/** Client connection handler
+ *
+ * @param callid	ID of incoming call or 0 if connection initiated from
+ *			inside using async_connect_to_me()
+ * @param call		Incoming call or 0 if connection initiated from inside
+ * @param arg		Local argument passed from async_new_connection() or
+ *			async_connect_to_me()
+ */
+typedef void (*async_client_conn_t)(ipc_callid_t, ipc_call_t *, void *);
+
+/** Interrupt handler */
+typedef void (*async_interrupt_handler_t)(ipc_callid_t, ipc_call_t *);
 
 /** Exchange management style
@@ -166,5 +177,5 @@
 
 extern fid_t async_new_connection(sysarg_t, sysarg_t, ipc_callid_t,
-    ipc_call_t *, async_client_conn_t);
+    ipc_call_t *, async_client_conn_t, void *);
 
 extern void async_usleep(suseconds_t);
@@ -177,5 +188,5 @@
 
 extern void async_set_client_connection(async_client_conn_t);
-extern void async_set_interrupt_received(async_client_conn_t);
+extern void async_set_interrupt_received(async_interrupt_handler_t);
 
 /*
@@ -351,5 +362,5 @@
 
 extern int async_connect_to_me(async_exch_t *, sysarg_t, sysarg_t, sysarg_t,
-    async_client_conn_t);
+    async_client_conn_t, void *);
 
 extern int async_hangup(async_sess_t *);
Index: uspace/lib/c/include/async_obsolete.h
===================================================================
--- uspace/lib/c/include/async_obsolete.h	(revision 9c0242b0b40302f92f8d0ac933b78ff30bf0348d)
+++ uspace/lib/c/include/async_obsolete.h	(revision ef15fbbac0915e003c970e47614ca22e47e3ed96)
@@ -198,5 +198,5 @@
 
 extern int async_obsolete_connect_to_me(int, sysarg_t, sysarg_t, sysarg_t,
-    async_client_conn_t);
+    async_client_conn_t, void *);
 extern int async_obsolete_connect_me_to(int, sysarg_t, sysarg_t, sysarg_t);
 extern int async_obsolete_connect_me_to_blocking(int, sysarg_t, sysarg_t, sysarg_t);