Index: kernel/generic/src/ipc/ipc.c
===================================================================
--- kernel/generic/src/ipc/ipc.c	(revision 43e2cbcf82bf0d553c0cb190d4043a6eed86a617)
+++ kernel/generic/src/ipc/ipc.c	(revision 0b005997aa705c5c511941d3a843eab28f34def7)
@@ -79,5 +79,5 @@
 	call->forget = false;
 	call->sender = NULL;
-	call->callerbox = &TASK->answerbox;
+	call->callerbox = NULL;
 	call->buffer = NULL;
 }
@@ -292,5 +292,6 @@
 	spinlock_unlock(&call->forget_lock);
 
-	answerbox_t *callerbox = call->callerbox;
+	answerbox_t *callerbox = call->callerbox ? call->callerbox :
+	    &call->sender->answerbox;
 	bool do_lock = ((!selflocked) || (callerbox != &TASK->answerbox));