diff --git a/.gitignore b/.gitignore
index 62b788c..e2f81da 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,6 +17,7 @@ coverage
 web/scss/.sass-cache/
 
 api/thumbnails/
+api/logs/
 
 build/
 
diff --git a/api/phenome10k/routes/files.py b/api/phenome10k/routes/files.py
index 2e61e20..8939184 100644
--- a/api/phenome10k/routes/files.py
+++ b/api/phenome10k/routes/files.py
@@ -6,8 +6,8 @@
 from flask import Blueprint, redirect, url_for, send_file
 from flask import Response, current_app, send_from_directory
 from flask import request
-from flask.helpers import safe_join
 from werkzeug.exceptions import NotFound, BadRequest
+from werkzeug.utils import safe_join
 
 from ._decorators import login_required, requires_contributor
 from ._utils import ensure_editable
@@ -106,8 +106,12 @@ def send_uploads(path):
         except FileExistsError:
             pass
 
-        height = im.height * width / im.width
-        im.thumbnail((width, height))
+        height = im.height * width // im.width
+        try:
+            im.thumbnail((width, height))
+        except OSError:
+            # if this didn't work, the image is broken
+            raise NotFound()
         byte_io = io.BytesIO()
         im.save(byte_io, format='PNG')
         im.save(thumbnail_file, format='PNG')
diff --git a/docker-compose.yml b/docker-compose.yml
index 866c9e6..e1dd3dd 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,5 +1,3 @@
-version: '3'
-
 services:
   data:
     image: mariadb:jammy