diff --git a/api/funkwhale_api/common/serializers.py b/api/funkwhale_api/common/serializers.py
index c754540c9..f1f332d13 100644
--- a/api/funkwhale_api/common/serializers.py
+++ b/api/funkwhale_api/common/serializers.py
@@ -219,7 +219,7 @@ class StripExifImageField(serializers.ImageField):
         with io.BytesIO() as output:
             image_without_exif.save(
                 output,
-                format=PIL.Image.EXTENSION[os.path.splitext(file_obj.name)[-1]],
+                format=PIL.Image.EXTENSION[os.path.splitext(file_obj.name)[-1].lower()],
                 quality=100,
             )
             content = output.getvalue()