diff --git a/docs/reference/Image.rst b/docs/reference/Image.rst
index bf173ace9..2f4c9af99 100644
--- a/docs/reference/Image.rst
+++ b/docs/reference/Image.rst
@@ -486,11 +486,12 @@ Used to specify the quantization method to use for the :meth:`~Image.quantize` m
 
 .. data:: MEDIANCUT
 
-    Median cut. Default method, except for RGBA images.
+    Median cut. Default method, except for RGBA images. This method does not support
+    RGBA images.
 
 .. data:: MAXCOVERAGE
 
-    Maximum coverage.
+    Maximum coverage. This method does not support RGBA images.
 
 .. data:: FASTOCTREE
 
diff --git a/src/PIL/Image.py b/src/PIL/Image.py
index bec6f3f64..0bfd1da80 100644
--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
@@ -1062,8 +1062,9 @@ class Image:
 
                        By default, :data:`MEDIANCUT` will be used.
 
-                       The exception to this is RGBA images. RGBA images use
-                       :data:`FASTOCTREE` by default instead.
+                       The exception to this is RGBA images. :data:`MEDIANCUT` and
+                       :data:`MAXCOVERAGE` do not support RGBA images, so
+                       :data:`FASTOCTREE` is used by default instead.
         :param kmeans: Integer
         :param palette: Quantize to the palette of given
                         :py:class:`PIL.Image.Image`.