diff --git a/docs/changes.rst b/docs/changes.rst
index 1913a26a..ea763d51 100644
--- a/docs/changes.rst
+++ b/docs/changes.rst
@@ -32,6 +32,8 @@ all releases are available on `PyPI <https://pypi.org/project/pytask>`_ and
 - :gh:`107` adds and new hook ``pytask_unconfigure`` which makes pytask return
   :func:`pdb.set_trace` at the end of a session which allows to use ``breakpoint()``
   inside test functions using pytask.
+- :gh:`109` makes pytask require networkx>=2.4 since previous versions fail with Python
+  3.9.
 
 
 0.0.14 - 2021-03-23
diff --git a/setup.cfg b/setup.cfg
index 01816e7b..a9d35dbb 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -37,7 +37,7 @@ install_requires =
     attrs>=17.4.0
     click
     click-default-group
-    networkx
+    networkx>=2.4
     pluggy
     pony>=0.7.13
     rich
diff --git a/tox.ini b/tox.ini
index 81ed7625..19f0a971 100644
--- a/tox.ini
+++ b/tox.ini
@@ -21,7 +21,7 @@ conda_deps =
     attrs
     click
     click-default-group
-    networkx
+    networkx>=2.4
     pluggy
     pony >= 0.7.13
     rich