Index: kernel/generic/include/ipc/sysipc.h
===================================================================
--- kernel/generic/include/ipc/sysipc.h	(revision 1ef0fc3af9d3036d613efbe2d4cfb0ce271abed0)
+++ kernel/generic/include/ipc/sysipc.h	(revision d7e45c8be7315ef77eefc2b926977723f9feb2df)
@@ -57,5 +57,5 @@
 unative_t sys_ipc_forward_slow(unative_t callid, unative_t phoneid,
     ipc_data_t *data, int mode);
-unative_t sys_ipc_hangup(int phoneid);
+unative_t sys_ipc_hangup(unative_t phoneid);
 unative_t sys_ipc_register_irq(inr_t inr, devno_t devno, unative_t method,
     irq_code_t *ucode);
Index: kernel/generic/src/ipc/sysipc.c
===================================================================
--- kernel/generic/src/ipc/sysipc.c	(revision 1ef0fc3af9d3036d613efbe2d4cfb0ce271abed0)
+++ kernel/generic/src/ipc/sysipc.c	(revision d7e45c8be7315ef77eefc2b926977723f9feb2df)
@@ -956,5 +956,5 @@
  * @return		Return 0 on success or an error code.
  */
-unative_t sys_ipc_hangup(int phoneid)
+unative_t sys_ipc_hangup(unative_t phoneid)
 {
 	phone_t *phone;