diff --git a/plone/scale/scale.py b/plone/scale/scale.py
index 3c3953b..01ba778 100644
--- a/plone/scale/scale.py
+++ b/plone/scale/scale.py
@@ -67,8 +67,8 @@ def scaleImage(
     The `width`, `height`, `mode` parameters will be passed to
     :meth:`scalePILImage`, which performs the actual scaling.
 
-    The generated image is a JPEG image, unless the original is a PNG or GIF
-    image. This is needed to make sure alpha channel information is
+    The generated image is a JPEG image, unless the original is a WEBP, PNG
+    or GIF image. This is needed to make sure alpha channel information is
     not lost, which JPEG does not support.
     """
     if isinstance(image, (bytes, str)):
@@ -113,7 +113,7 @@ def scaleImage(
         else:
             # All other formats only process a single frame
             if format_ not in ("PNG", "GIF", "WEBP"):
-                # Always generate JPEG, except if format is PNG or GIF.
+                # Always generate JPEG, except if format is WEBP, PNG or GIF.
                 format_ = "JPEG"
             image, format_ = scaleSingleFrame(
                 img,