diff --git a/web/src/lightbox.ts b/web/src/lightbox.ts
index b117c702e4..e956e81da1 100644
--- a/web/src/lightbox.ts
+++ b/web/src/lightbox.ts
@@ -212,6 +212,10 @@ export function clear_for_testing(): void {
     asset_map.clear();
 }
 
+export function invalidate_asset_map_of_message(message_id: number): void {
+    asset_map.delete(message_id);
+}
+
 function set_selected_media_element($media: JQuery<HTMLMediaElement | HTMLImageElement>): void {
     // Clear out any previously selected element
     $(".media-to-select-in-lightbox-list").removeClass("media-to-select-in-lightbox-list");
diff --git a/web/src/message_events.ts b/web/src/message_events.ts
index 00945eca34..9229ccc4b0 100644
--- a/web/src/message_events.ts
+++ b/web/src/message_events.ts
@@ -17,6 +17,7 @@ import * as direct_message_group_data from "./direct_message_group_data.ts";
 import * as drafts from "./drafts.ts";
 import * as echo from "./echo.ts";
 import type {Filter} from "./filter.ts";
+import * as lightbox from "./lightbox.ts";
 import * as message_edit from "./message_edit.ts";
 import * as message_edit_history from "./message_edit_history.ts";
 import * as message_events_util from "./message_events_util.ts";
@@ -458,6 +459,10 @@ export function update_messages(events: UpdateMessageEvent[]): void {
 
                 // Update raw_content, so that editing a few times in a row is fast.
                 anchor_message.raw_content = event.content;
+
+                // Editing a message may change the titles for linked
+                // media, so we must invalidate the asset map.
+                lightbox.invalidate_asset_map_of_message(event.message_id);
             }
 
             if (unread.update_message_for_mention(anchor_message, any_message_content_edited)) {