diff --git a/doc/conf.py b/doc/conf.py
index f0add1f9..db799ead 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -71,7 +71,7 @@
 #
 html_theme = 'sphinx_rtd_theme'
 html_theme_options = {
-    'display_version': True,
+    'version_selector': True,
 }
 
 # Add any paths that contain custom static files (such as style sheets) here,
diff --git a/vivarium/core/serialize_test.py b/vivarium/core/serialize_test.py
index fa8d5071..fa7e2447 100644
--- a/vivarium/core/serialize_test.py
+++ b/vivarium/core/serialize_test.py
@@ -197,7 +197,8 @@ def test_non_string_keys() -> None:
     except TypeError as e:
         expected_error = (
             "These paths end in incompatible non-string or Numpy string " +
-            "keys: [(np.str_('1'),), (1,), ('string', 'string2', 'string3', np.str_('1'))]")
+            "keys: [(np.str_('1'),), (1,), ('string', 'string2', 'string3', " +
+            "np.str_('1'))]")
         assert str(e) == expected_error