diff --git a/migration.js b/migration.js
index d9e3a39..127ec59 100644
--- a/migration.js
+++ b/migration.js
@@ -12,7 +12,7 @@ async function addUpdatedDate() {
 	let vehicles = await collection.find().toArray();
 	for(let vehicle of vehicles) {
 		let updatedDate = vehicle.addedDate;
-		if(vehicle.events.length > 0) {
+		if(vehicle.events && vehicle.events.length > 0) {
 			let lastEvent = vehicle.events.reduce((acc, cur) => acc.date > cur.date ? acc : cur);
 			updatedDate = Math.max(1000*lastEvent.date, vehicle.addedDate);
 		}