diff --git a/sys/platform/pc32/i386/trap.c b/sys/platform/pc32/i386/trap.c
index e9b125d..3928caf 100644
--- a/sys/platform/pc32/i386/trap.c
+++ b/sys/platform/pc32/i386/trap.c
@@ -240,6 +240,8 @@ userret(struct lwp *lp, struct trapframe *frame, int sticks)
 	void (*hook)(void);
 	int sig;
 
+	KKASSERT(lp->lwp_thread->td_toks_stop ==
+		 &lp->lwp_thread->td_toks_array[0]);
 	if (p->p_userret != NULL) {
 		hook = p->p_userret;
 		p->p_userret = NULL;