diff --git a/src/rougail/tiramisu.py b/src/rougail/tiramisu.py
index 5ad376edd..5c5c4a37d 100644
--- a/src/rougail/tiramisu.py
+++ b/src/rougail/tiramisu.py
@@ -36,6 +36,8 @@ class ConvertDynOptionDescription(DynOptionDescription):
     Suffix could also contain invalid character, so we should "normalize" it
     """
     def convert_suffix_to_path(self, suffix):
+        if suffix is None:
+            return suffix
         if not isinstance(suffix, str):
             suffix = str(suffix)
         return normalize_family(suffix)
diff --git a/src/rougail/update.py b/src/rougail/update.py
index c9c0ef47c..44f2e2fb0 100644
--- a/src/rougail/update.py
+++ b/src/rougail/update.py
@@ -116,7 +116,7 @@ class RougailUpgrade:
         if variables is None:
             return root
         paths = self._get_path_variables(variables,
-                                         namespace == self.rougailconfig['variable_namespace'],
+                                         namespace == 'configuration',
                                          namespace,
                                          )
         constraints = root.find('constraints')
@@ -334,7 +334,7 @@ class RougailUpgrade:
                             subsubsubelement.attrib['mandatory'] = 'True'
                         if subsubsubelement.attrib['name'] in upgrade_help.get('variables', {}).get('type', {}):
                             subsubsubelement.attrib['type'] = upgrade_help.get('variables', {}).get('type', {})[subsubsubelement.attrib['name']]
-                        if namespace == self.rougailconfig['variable_namespace']:
+                        if namespace == 'configuration':
                             path = subsubsubelement.attrib['name']
                             npath = normalize_family(subsubsubelement.attrib['name'])
                         else: