diff --git a/app/views/scodoc.py b/app/views/scodoc.py
index 02bc1fb11..394dfe833 100644
--- a/app/views/scodoc.py
+++ b/app/views/scodoc.py
@@ -266,14 +266,16 @@ def _return_logo(name="header", dept_id="", small=False, strict: bool = True):
         suffix = logo.suffix
         if small:
             with PILImage.open(logo.filepath) as im:
-                im.thumbnail(SMALL_SIZE)
-                stream = io.BytesIO()
                 # on garde le même format (on pourrait plus simplement générer systématiquement du JPEG)
                 fmt = {  # adapt suffix to be compliant with PIL save format
                     "PNG": "PNG",
                     "JPG": "JPEG",
                     "JPEG": "JPEG",
                 }[suffix.upper()]
+                if fmt == "JPEG":
+                    im = im.convert("RGB")
+                im.thumbnail(SMALL_SIZE)
+                stream = io.BytesIO()
                 im.save(stream, fmt)
                 stream.seek(0)
                 return send_file(stream, mimetype=f"image/{fmt}")