diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index f776fd42..73f7595 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -813,9 +813,11 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev,
 	if (ret == -ENOPROTOOPT) {
 		dev_dbg(ec_dev->dev,
 			"GET_NEXT_EVENT returned invalid version error.\n");
+		mutex_lock(&ec_dev->lock);
 		ret = cros_ec_get_host_command_version_mask(ec_dev,
 							EC_CMD_GET_NEXT_EVENT,
 							&ver_mask);
+		mutex_unlock(&ec_dev->lock);
 		if (ret < 0 || ver_mask == 0)
 			/*
 			 * Do not change the MKBP supported version if we can't