diff --git a/TODO.md b/TODO.md
index 6279f724..53947060 100644
--- a/TODO.md
+++ b/TODO.md
@@ -153,8 +153,6 @@
 
 ## Backend
 
-- Have a `Thubmnail.from_existing_file()` to be called after generating and
-  and uploading a thumbnail, like the equivalent `Media.from_existing_file()`
 - Saving the room settings
 - Refetch profile after manual profile change, don't wait for a room event
 
diff --git a/src/backend/matrix_client.py b/src/backend/matrix_client.py
index 96e0d74a..11152861 100644
--- a/src/backend/matrix_client.py
+++ b/src/backend/matrix_client.py
@@ -471,8 +471,7 @@ class MatrixClient(nio.AsyncClient):
 
                     thumb_url, _, thumb_crypt_dict = await self.upload(
                         lambda *_: thumb_data,
-                        filename =
-                            f"{path.stem}_sample{''.join(path.suffixes)}",
+                        filename = f"{path.stem}_sample{path.suffix}",
                         filesize = thumb_info.size,
                         encrypt  = encrypt,
                         monitor  = monitor,
@@ -489,6 +488,7 @@ class MatrixClient(nio.AsyncClient):
                     await Thumbnail.from_bytes(
                         self.backend.media_cache,
                         thumb_url,
+                        path.name,
                         thumb_data,
                         wanted_size = (content["info"]["w"],
                                        content["info"]["h"]),
diff --git a/src/backend/media_cache.py b/src/backend/media_cache.py
index b524138a..cba15be8 100644
--- a/src/backend/media_cache.py
+++ b/src/backend/media_cache.py
@@ -193,13 +193,14 @@ class Media:
         cls,
         cache:     "MediaCache",
         mxc:       str,
+        filename:  str,
         data:      bytes,
         overwrite: bool = False,
         **kwargs,
     ) -> "Media":
         """Create a cached file from bytes data and return a `Media` for it."""
 
-        media = cls(cache, mxc, {}, **kwargs)  # type: ignore
+        media = cls(cache, mxc, filename, {}, **kwargs)  # type: ignore
         media.local_path.parent.mkdir(parents=True, exist_ok=True)
 
         if not media.local_path.exists() or overwrite: