https://github.com/jarus/flask-testing/commit/c969b41b31f60a5a8bacd44b3eb63d1642f2d8bf
diff --git a/flask_testing/utils.py b/flask_testing/utils.py
index add12ef..9b479df 100644
--- a/flask_testing/utils.py
+++ b/flask_testing/utils.py
@@ -143,8 +143,8 @@ def _post_teardown(self):
 
         if _is_signals:
             template_rendered.disconnect(self._add_template)
-        if hasattr(self, '_true_render'):
-            templating._render = self._true_render
+        if hasattr(self, '_original_template_render'):
+            templating._render = self._original_template_render
 
         if self.run_gc_after_test:
             gc.collect()