diff --git a/sys/src/kern/port/devproc.c b/sys/src/kern/port/devproc.c
index d6b57dc..9003ff9 100644
--- a/sys/src/kern/port/devproc.c
+++ b/sys/src/kern/port/devproc.c
@@ -1325,6 +1325,8 @@ procstopwait(Proc *p, int ctl)
 		error(Eprocdied);
 	if(ctl != 0)
 		p->procctl = ctl;
+	if(p == up)
+		return;
 	p->pdbg = up;
 	qunlock(&p->debug);
 	up->psstate = "Stopwait";