because nothing ever is easy in life

tox.ini

@@ -33,7 +33,7 @@ description = invoke sphinx-build to build HTML docs
 basepython = python3.7
 deps =
     sphinx >= 3.5.1, < 4
-    m2r
+    m2r2 == 0.3.2
 ignore_errors = true
 commands =
     # https://tox.readthedocs.io/en/latest/example/documentation.html