diff --git a/kernel/acct.c b/kernel/acct.c
index ca56190..69a40c9 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -485,12 +485,9 @@
 	ac.ac_ppid = current->parent->tgid;
 #endif
 
-	mutex_lock(&tty_mutex);
-	tty = get_current_tty();
-	ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
-	mutex_unlock(&tty_mutex);
-
 	spin_lock_irq(&current->sighand->siglock);
+	tty = current->signal->tty;
+	ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
 	ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
 	ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
 	ac.ac_flag = pacct->ac_flag;