--- sys/kern/tty.c.orig
+++ sys/kern/tty.c
@@ -231,9 +231,6 @@
 
 	tp->t_flags |= TF_OPENCLOSE;
 
-	/* Stop asynchronous I/O. */
-	funsetown(&tp->t_sigio);
-
 	/* Remove console TTY. */
 	if (constty == tp)
 		constty_clear();
@@ -1124,6 +1121,9 @@
 		return;
 	}
 
+	/* Stop asynchronous I/O. */
+	funsetown(&tp->t_sigio);
+
 	/* TTY can be deallocated. */
 	dev = tp->t_dev;
 	tp->t_dev = NULL;