diff --git a/server.py b/server.py
index 979fa87..353196a 100644
--- a/server.py
+++ b/server.py
@@ -1,3 +1,4 @@
+import io
 import os
 
 import fastapi
@@ -105,13 +106,14 @@ URL_OG_TAGS = [
 ]
 
 
-def upload_media(domain: str, access_token: str, file: bytes, filename: str, content_type: str):
+def upload_media(domain: str, access_token: str, file: io.BytesIO, filename: str, content_type: str):
+    file.seek(0)
     logging.info(
         "Creating media at %r called %r with the content type %r and %d bytes",
         domain,
         filename,
         content_type,
-        len(file)
+        len(file.getvalue())
     )
 
     response = httpx.post(
@@ -196,11 +198,14 @@ def preview_url(
                 if response_media.status_code not in range(200, 300):
                     logging.warning("Failed to fetch media: %r - HTTP %s", _url, response_media.status_code)
                     og_tags.pop(tag_name, None)
+                elif not response_media.headers.get("content-type", "").startswith(("image/", "video/", "audio/")):
+                    logging.warning("Failed to fetch media: %r - not a media type", _url)
+                    og_tags.pop(tag_name, None)
                 else:
                     upload_response = upload_media(
                         domain,
                         access_token,
-                        response_media.content,
+                        io.BytesIO(response_media.content),
                         Path(httpx.URL(_url).path).name,
                         response_media.headers.get("content-type", "")
                     )