diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 6d19a00..a969adf 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -166,6 +166,18 @@ static struct timespec total_sleep_time;
  */
 struct timespec raw_time;
 
+/* must hold write on xtime_lock */
+static void timekeeping_update(bool clearntp)
+{
+	if (clearntp) {
+		timekeeper.ntp_error = 0;
+		ntp_clear();
+	}
+	update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
+}
+
+
+
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
 
@@ -341,10 +353,7 @@ int do_settimeofday(struct timespec *tv)
 
 	update_xtime_cache(0);
 
-	timekeeper.ntp_error = 0;
-	ntp_clear();
-
-	update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
+	timekeeping_update(true);
 
 	write_sequnlock_irqrestore(&xtime_lock, flags);
 
@@ -832,8 +841,7 @@ void update_wall_time(void)
 	nsecs = clocksource_cyc2ns(offset, timekeeper.mult, timekeeper.shift);
 	update_xtime_cache(nsecs);
 
-	/* check to see if there is a new clocksource to use */
-	update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
+	timekeeping_update(false);
 }
 
 /**