diff --git a/src/repositories/InMemoryNotificationRepository.ts b/src/repositories/InMemoryNotificationRepository.ts
index d93af1f..bd1db3f 100644
--- a/src/repositories/InMemoryNotificationRepository.ts
+++ b/src/repositories/InMemoryNotificationRepository.ts
@@ -21,6 +21,16 @@ export class InMemoryNotificationRepository implements NotificationRepository {
 
   private listeners: Listener[] = [];
 
+  constructor() {
+    this.getAllNotificationsForShuttleAndStopId = this.getAllNotificationsForShuttleAndStopId.bind(this);
+    this.getSecondsThresholdForNotificationIfExists = this.getSecondsThresholdForNotificationIfExists.bind(this);
+    this.deleteNotificationIfExists = this.deleteNotificationIfExists.bind(this);
+    this.addOrUpdateNotification = this.addOrUpdateNotification.bind(this);
+    this.isNotificationScheduled = this.isNotificationScheduled.bind(this);
+    this.subscribeToNotificationChanges = this.subscribeToNotificationChanges.bind(this);
+    this.unsubscribeFromNotificationChanges = this.unsubscribeFromNotificationChanges.bind(this);
+  }
+
   async getAllNotificationsForShuttleAndStopId(shuttleId: string, stopId: string) {
     const tuple = new TupleKey(shuttleId, stopId);
     if (this.deviceIdsToDeliverTo[tuple.toString()] === undefined) {
@@ -51,7 +61,8 @@ export class InMemoryNotificationRepository implements NotificationRepository {
   }
 
   async isNotificationScheduled(lookupArguments: NotificationLookupArguments): Promise<boolean> {
-    return await this.getSecondsThresholdForNotificationIfExists(lookupArguments) !== null;
+    const threshold = await this.getSecondsThresholdForNotificationIfExists(lookupArguments);
+    return threshold !== null;
   }
 
   async addOrUpdateNotification({