diff --git a/g13gui/g13gui/observer/observer.py b/g13gui/g13gui/observer/observer.py
index c8ca1f2..34386fa 100644
--- a/g13gui/g13gui/observer/observer.py
+++ b/g13gui/g13gui/observer/observer.py
@@ -11,6 +11,8 @@ class Observer(object):
     def _makeChangeTriggerKeys(self, changeType, keys):
         result = []
         if keys != Subject.AllKeys:
+            if type(keys) != set:
+                keys = {keys}
             for key in keys:
                 result.append((changeType, key))
         else: