diff --git a/setup.py b/setup.py
index e8eb1d45..0ea76eae 100644
--- a/setup.py
+++ b/setup.py
@@ -79,7 +79,7 @@ def absolute_links(txt):
           'reports': ['Jinja2'],
           'combine': ['python-libcombine>=0.2.6'],
           'doc': [
-              'sphinx>=3.5.3',
+              'sphinx>=3.5.3, !=5.1.0',
               'sphinxcontrib-napoleon>=0.7',
               'sphinx-markdown-tables>=0.0.15',
               'sphinx-rtd-theme>=0.5.1',