diff --git a/src/app/home/course/course.page.ts b/src/app/home/course/course.page.ts
index 137ec5c..e4f89b1 100644
--- a/src/app/home/course/course.page.ts
+++ b/src/app/home/course/course.page.ts
@@ -250,15 +250,15 @@ export class CoursePage implements OnInit, AfterViewInit, OnDestroy {
             duration: 0
         };
         this.lastPlayedVideoKey = Object.values(history).map(h => h.video_id).sort((a, b) => {
-            // force history[b].updated_at to be a string
+            // force history[b].played_at to be a string
             // @ts-ignore
-            return ('' + history[b].updated_at).localeCompare(history[a].updated_at);
+            return ('' + history[b].played_at).localeCompare(history[a].played_at);
         }).slice(0, 1)[0] ?? null;
         const videoInfo = Object.values(videos).map(lecture => {
             lecture.history = history[lecture.id] ?? ((lecture.id in evaluations && lecture.duration) ? { // If evaluation exists, treat as watched
                 end_time: lecture.duration,
-                updated_at: null,
-            } : {end_time: null, updated_at: null});
+                played_at: null,
+            } : {end_time: null, played_at: null});
             if (lecture.duration) {
                 progress.duration -= -lecture.duration;
                 if (lecture.history.end_time) {
diff --git a/src/app/man.service.ts b/src/app/man.service.ts
index 24df606..76c9ee8 100644
--- a/src/app/man.service.ts
+++ b/src/app/man.service.ts
@@ -112,7 +112,7 @@ export class ManService {
                 const records = data?.records ?? {};
                 if (update) {
                     if (!records[update.video_id] ||
-                        (records[update.video_id].updated_at < update.updated_at)) {
+                        (records[update.video_id].played_at < update.played_at)) {
                         records[update.video_id] = update;
                     }
                 }
@@ -211,7 +211,7 @@ export interface CourseListResponse {
         }[];
     };
     last_fetched_at: string;
-    last_played: { video: Lecture, updated_at: string, end_time: number } | null;
+    last_played: { video: Lecture, played_at: string, end_time: number } | null;
 }
 
 export interface EvaluationRecord {
diff --git a/src/app/play-tracker.service.ts b/src/app/play-tracker.service.ts
index eafb561..a879b03 100644
--- a/src/app/play-tracker.service.ts
+++ b/src/app/play-tracker.service.ts
@@ -1,5 +1,5 @@
 import {inject, Injectable} from '@angular/core';
-import {first, map, mergeMap, switchMap, tap} from 'rxjs/operators';
+import {first, map, switchMap, tap} from 'rxjs/operators';
 import {fromEventPattern, Observable} from 'rxjs';
 import {FieldValue, Timestamp} from '@angular/fire/firestore';
 import Pusher from 'pusher-js';
@@ -61,7 +61,7 @@ export interface PlayHistory {
 export interface PlayHistoryValue {
     duration?: number | null;
     end_time: number;
-    updated_at: Timestamp | FieldValue;
+    played_at: Timestamp | FieldValue;
     video_id?: number;
     year?: string;
     course?: string;