Index: kernel/generic/src/ipc/ipc.c
===================================================================
--- kernel/generic/src/ipc/ipc.c	(revision 01c3bb491370247ba1459d7e381e27022f09fed4)
+++ kernel/generic/src/ipc/ipc.c	(revision 96258fcbd61a26b0de930d1c77a5891bfdd010a9)
@@ -838,4 +838,17 @@
 }
 
+static bool call_cap_cleanup_cb(cap_t *cap, void *arg)
+{
+	/*
+	 * Here we just free the capability and release the kobject.
+	 * The kernel answers the remaining calls elsewhere in ipc_cleanup().
+	 */
+	kobject_t *kobj = cap_unpublish(cap->task, cap->handle,
+	    KOBJECT_TYPE_CALL);
+	kobject_put(kobj);
+	cap_free(cap->task, cap->handle);
+	return true;
+}
+
 /** Clean up all IPC communication of the current task.
  *
@@ -874,4 +887,8 @@
 	ipc_kbox_cleanup();
 #endif
+
+	/* Destroy all call capabilities */
+	caps_apply_to_kobject_type(TASK, KOBJECT_TYPE_CALL, call_cap_cleanup_cb,
+	    NULL);
 	
 	/* Answer all messages in 'calls' and 'dispatched_calls' queues */