diff --git a/app/scodoc/sco_preferences.py b/app/scodoc/sco_preferences.py
index ccdc6764..e5a27411 100644
--- a/app/scodoc/sco_preferences.py
+++ b/app/scodoc/sco_preferences.py
@@ -181,7 +181,7 @@ def _convert_pref_type(p, pref_spec):
 
 def _get_pref_default_value_from_config(name, pref_spec):
     """get default value store in application level config.
-    If not found, use defalut value hardcoded in pref_spec.
+    If not found, use default value hardcoded in pref_spec.
     """
     # XXX va changer avec la nouvelle base
     # search in scu.CONFIG
@@ -1892,7 +1892,7 @@ class BasePreferences(object):
 
     def get(self, formsemestre_id, name):
         """Returns preference value.
-        If global_lookup, when no value defined for this semestre, returns global value.
+        when no value defined for this semestre, returns global value.
         """
         params = {
             "dept_id": self.dept_id,
@@ -1902,7 +1902,7 @@ class BasePreferences(object):
         cnx = ndb.GetDBConnexion()
         plist = self._editor.list(cnx, params)
         if not plist:
-            del params["formsemestre_id"]
+            params["formsemestre_id"] = None
             plist = self._editor.list(cnx, params)
             if not plist:
                 return self.default[name]