diff --git a/tox.ini b/tox.ini
index 4a92134..6dc40ee 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,6 +4,12 @@ isolated_build = True
 
 [testenv]
 deps =
+    # This is a stopgap dependency pin.
+    # https://github.com/pypa/readme_renderer/issues/310
+    # This can be removed when Python 3.8 is no longer supported,
+    # or after the test suite is updated to resolve this issue.
+    docutils==0.20.1
+
     pytest
     pytest-cov
     pytest-icdiff