diff --git a/crates/matrix-sdk-ui/tests/integration/timeline/media.rs b/crates/matrix-sdk-ui/tests/integration/timeline/media.rs
index d35cbbcfe..2987ce12c 100644
--- a/crates/matrix-sdk-ui/tests/integration/timeline/media.rs
+++ b/crates/matrix-sdk-ui/tests/integration/timeline/media.rs
@@ -574,7 +574,7 @@ async fn test_send_media_with_thumbnail() -> TestResult {
             .media()
             .get_media_content(
                 &MediaRequestParameters {
-                    source: content.source.clone(),
+                    source: MediaSource::Plain(thumbnail_uri.clone()),
                     format: MediaFormat::Thumbnail(MediaThumbnailSettings::new(
                         uint!(37),
                         uint!(13),
diff --git a/crates/matrix-sdk/src/send_queue/upload.rs b/crates/matrix-sdk/src/send_queue/upload.rs
index 5be0fb626..e45bacc1e 100644
--- a/crates/matrix-sdk/src/send_queue/upload.rs
+++ b/crates/matrix-sdk/src/send_queue/upload.rs
@@ -978,11 +978,12 @@ async fn update_media_cache_keys_after_upload(
                 .await
             {
                 Ok(Some(thumbnail_content)) => {
-                    // Cache this as a thumbnail for the original source, in the media store.
+                    // Also cache this as a thumbnail for the thumbnail, in the media store; the
+                    // ElementX apps expect that specific format for thumbnails.
                     media_store
                         .add_media_content(
                             &MediaRequestParameters {
-                                source: sent_media.file.clone(),
+                                source: remote_thumbnail_source.clone(),
                                 format: MediaFormat::Thumbnail(MediaThumbnailSettings::new(
                                     width, height,
                                 )),
diff --git a/crates/matrix-sdk/tests/integration/send_queue.rs b/crates/matrix-sdk/tests/integration/send_queue.rs
index af9a91ea6..77829bf15 100644
--- a/crates/matrix-sdk/tests/integration/send_queue.rs
+++ b/crates/matrix-sdk/tests/integration/send_queue.rs
@@ -2148,13 +2148,13 @@ async fn test_media_uploads() {
         .expect("media should be found");
     assert_eq!(thumbnail_media_as_file, b"thumbnail");
 
-    // The thumbnail can be retrieved as a thumbnail of the original media, using
+    // The thumbnail can be retrieved as a thumbnail of itself, using
     // the sent media MXC URI:
     let thumbnail_media_as_thumbnail = client
         .media()
         .get_media_content(
             &MediaRequestParameters {
-                source: new_content.source,
+                source: new_thumbnail_source.clone(),
                 format: MediaFormat::Thumbnail(MediaThumbnailSettings::new(uint!(37), uint!(13))),
             },
             true,