diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index cc63f9baa481..538297ef8255 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -221,8 +221,11 @@ static int pwm_sifive_clock_notifier(struct notifier_block *nb,
 	struct pwm_sifive_ddata *ddata =
 		container_of(nb, struct pwm_sifive_ddata, notifier);
 
-	if (event == POST_RATE_CHANGE)
+	if (event == POST_RATE_CHANGE) {
+		mutex_lock(&ddata->lock);
 		pwm_sifive_update_clock(ddata, ndata->new_rate);
+		mutex_unlock(&ddata->lock);
+	}
 
 	return NOTIFY_OK;
 }