diff --git a/functional/test_default_parameters.py b/functional/test_default_parameters.py
index a33823f..7201969 100644
--- a/functional/test_default_parameters.py
+++ b/functional/test_default_parameters.py
@@ -77,7 +77,7 @@
             # remove the default from the parameter in the nested template.
             ntempl = yaml.safe_load(self.nested_template)
             del ntempl['parameters']['length']['default']
-            nested_template = yaml.dump(ntempl)
+            nested_template = yaml.safe_dump(ntempl)
         else:
             nested_template = self.nested_template