Index: kernel/generic/src/ipc/ipc.c
===================================================================
--- kernel/generic/src/ipc/ipc.c	(revision 69eac4aa01fc2a2eb07931b006cf18b42b9f0bd0)
+++ kernel/generic/src/ipc/ipc.c	(revision 57edf88766c6a50640bebb11c0cb6b11bd697ffc)
@@ -162,5 +162,5 @@
 void ipc_phone_init(phone_t *phone)
 {
-	mutex_initialize(&phone->lock);
+	mutex_initialize(&phone->lock, MUTEX_PASSIVE);
 	phone->callee = NULL;
 	phone->state = IPC_PHONE_FREE;