diff --git a/docs/handbook/image-file-formats.rst b/docs/handbook/image-file-formats.rst
index 0355e1d18..bd565f79c 100644
--- a/docs/handbook/image-file-formats.rst
+++ b/docs/handbook/image-file-formats.rst
@@ -712,8 +712,8 @@ The :py:meth:`~PIL.Image.open` method sets the following attributes:
 **n_frames**
     Set to the number of images in the stack.
 
-A convenience method, :py:meth:`~PIL.Image.Image.convert2byte`, is provided for
-converting floating point data to byte data (mode ``L``)::
+A convenience method, :py:meth:`~PIL.SpiderImagePlugin.SpiderImageFile.convert2byte`,
+is provided for converting floating point data to byte data (mode ``L``)::
 
     im = Image.open('image001.spi').convert2byte()