diff --git a/setup.py b/setup.py
index de1c79b6c..eea026129 100644
--- a/setup.py
+++ b/setup.py
@@ -27,6 +27,7 @@ def get_setup_version(reponame):
         'pygraphviz',
         'nbsite >=0.7.1',
         'pydata-sphinx-theme',
+        'jinja2 <3.1', # API breakage
         'myst-parser',
         'nbconvert',
         'graphviz',