diff --git a/lib/widgets/lightbox.dart b/lib/widgets/lightbox.dart
index 7e4141db63..0067e508a6 100644
--- a/lib/widgets/lightbox.dart
+++ b/lib/widgets/lightbox.dart
@@ -171,21 +171,23 @@ class _LightboxPageLayoutState extends State<_LightboxPageLayout> {
         backgroundColor: appBarBackgroundColor,
         shape: const Border(), // Remove bottom border from [AppBarTheme]
         elevation: appBarElevation,
-
-        // TODO(#41): Show message author's avatar
-        title: RichText(
-          text: TextSpan(children: [
-            TextSpan(
-              text: '${widget.message.senderFullName}\n',
-
-              // Restate default
-              style: themeData.textTheme.titleLarge!.copyWith(color: appBarForegroundColor)),
-            TextSpan(
-              text: timestampText,
-
-              // Make smaller, like a subtitle
-              style: themeData.textTheme.titleSmall!.copyWith(color: appBarForegroundColor)),
-          ])),
+        title: Row(children: [
+          Avatar(size: 36, borderRadius: 36 / 8, userId: widget.message.senderId),
+          const SizedBox(width: 8),
+          Expanded(
+            child: RichText(
+              text: TextSpan(
+                children: [
+                  TextSpan(
+                    text: '${widget.message.senderFullName}\n',
+                    // Restate default
+                    style: themeData.textTheme.titleLarge!.copyWith(color: appBarForegroundColor)),
+                  TextSpan(
+                    text: timestampText,
+                    // Make smaller, like a subtitle
+                    style: themeData.textTheme.titleSmall!.copyWith(color: appBarForegroundColor)),
+                ]))),
+          ]),
         bottom: widget.buildAppBarBottom(context));
     }
 
diff --git a/test/widgets/lightbox_test.dart b/test/widgets/lightbox_test.dart
index 4a84f79b27..9a89f84b16 100644
--- a/test/widgets/lightbox_test.dart
+++ b/test/widgets/lightbox_test.dart
@@ -236,12 +236,16 @@ void main() {
       debugNetworkImageHttpClientProvider = null;
     });
 
-    testWidgets('app bar shows sender name and date', (tester) async {
+    testWidgets('app bar shows sender avatar, name and date', (tester) async {
       prepareBoringImageHttpClient();
       final timestamp = DateTime.parse("2024-07-23 23:12:24").millisecondsSinceEpoch ~/ 1000;
       final message = eg.streamMessage(sender: eg.otherUser, timestamp: timestamp);
       await setupPage(tester, message: message, thumbnailUrl: null);
 
+      // Check Avatar properties
+      final avatar = tester.widget<Avatar>(find.byType(Avatar));
+      check(avatar.userId).equals(message.senderId);
+
       // We're looking for a RichText, in the app bar, with both the
       // sender's name and the timestamp.
       final labelTextWidget = tester.widget<RichText>(