diff --git a/setup.py b/setup.py
index 706a5f0..08d9629 100644
--- a/setup.py
+++ b/setup.py
@@ -31,6 +31,7 @@ def version(*parts):
             'itk',
             'itk-thickness3d',
             'networkx',
+            'scikit-image',
             'SimpleITK',
             'vtk',
         ]
@@ -49,6 +50,7 @@ def version(*parts):
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: 3.9',
     ]
     , project_urls={
         'Source': 'https://github.com/K3D-tools/chunky3d',