Index: kernel/generic/include/ipc/sysipc.h
===================================================================
--- kernel/generic/include/ipc/sysipc.h	(revision f651e80e2ba6968d9e184dd8ca7fa6e5b779caaf)
+++ kernel/generic/include/ipc/sysipc.h	(revision 4bc73fa8bbcccf620136bf8a8217a30c0a840d89)
@@ -54,4 +54,6 @@
 unative_t sys_ipc_forward_fast(unative_t callid, unative_t phoneid,
     unative_t method, unative_t arg1, unative_t arg2, int mode);
+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_register_irq(inr_t inr, devno_t devno, unative_t method,
Index: kernel/generic/include/syscall/syscall.h
===================================================================
--- kernel/generic/include/syscall/syscall.h	(revision f651e80e2ba6968d9e184dd8ca7fa6e5b779caaf)
+++ kernel/generic/include/syscall/syscall.h	(revision 4bc73fa8bbcccf620136bf8a8217a30c0a840d89)
@@ -63,4 +63,5 @@
 	SYS_IPC_ANSWER_SLOW,
 	SYS_IPC_FORWARD_FAST,
+	SYS_IPC_FORWARD_SLOW,
 	SYS_IPC_WAIT,
 	SYS_IPC_HANGUP,