diff --git a/src/models/attachmentManager.ts b/src/models/attachmentManager.ts
index 1324846..a8a9a6c 100644
--- a/src/models/attachmentManager.ts
+++ b/src/models/attachmentManager.ts
@@ -138,8 +138,8 @@ export class AttachmentManager {
           try {
             let canvas: HTMLCanvasElement = document.createElement("canvas");
 
-            canvas.width = 320;
-            canvas.height = 240;
+            canvas.width = 640;
+            canvas.height = 480;
             let video: HTMLVideoElement = document.createElement("video");
             video.addEventListener("loadedmetadata", function () {
               if (video.videoWidth > THUMBNAIL_MAX_WIDTH || video.videoHeight > THUMBNAIL_MAX_HEIGHT) {
diff --git a/src/plugins/utils.js b/src/plugins/utils.js
index 05aa3f2..1231e49 100644
--- a/src/plugins/utils.js
+++ b/src/plugins/utils.js
@@ -24,8 +24,8 @@ export const ROOM_TYPE_CHANNEL = "im.keanu.room_type_channel";
 
 export const STATE_EVENT_ROOM_TYPE = "im.keanu.room_type";
 
-export const THUMBNAIL_MAX_WIDTH = 320;
-export const THUMBNAIL_MAX_HEIGHT = 320;
+export const THUMBNAIL_MAX_WIDTH = 640;
+export const THUMBNAIL_MAX_HEIGHT = 640;
 
 // Install extended localized format
 dayjs.extend(localizedFormat);