diff --git a/readthedocs/rtd_tests/tests/test_doc_builder.py b/readthedocs/rtd_tests/tests/test_doc_builder.py
index 894c8faa6cd..f3c305bee99 100644
--- a/readthedocs/rtd_tests/tests/test_doc_builder.py
+++ b/readthedocs/rtd_tests/tests/test_doc_builder.py
@@ -353,9 +353,14 @@ def test_write_js_data_docs_dir(self, checkout_path, run, generate_rtd_data):
         checkout_path.return_value = tmpdir
         generate_rtd_data.return_value = ''
 
+        python_env = Virtualenv(
+            version=self.version,
+            build_env=self.build_env,
+            config=None,
+        )
         self.searchbuilder = MkdocsHTML(
             build_env=self.build_env,
-            python_env=None
+            python_env=python_env,
         )
         self.searchbuilder.append_conf()