diff --git a/docs/environment.yml b/docs/environment.yml
index ed8a82f7..535226a1 100644
--- a/docs/environment.yml
+++ b/docs/environment.yml
@@ -12,3 +12,4 @@ dependencies:
 - scikit-image
 - sphinx
 - nbsphinx
+- packaging
diff --git a/setup.py b/setup.py
index 3492c4dc..be272c24 100644
--- a/setup.py
+++ b/setup.py
@@ -67,6 +67,7 @@
         'ipywidgets>=7.2.1',
         'ipydatawidgets>=1.1.1',
         'numpy',
+        'packaging',
         'traitlets',
     ],
     'extras_require': {