Index: UI/Scheduler/UIxCalendarSelector.m
--- UI/Scheduler/UIxCalendarSelector.m.orig
+++ UI/Scheduler/UIxCalendarSelector.m
@@ -204,7 +204,7 @@ _intValueFromHex (NSString *hexString)
           else
             synchronize = [folder synchronize];
 
-          acls = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithBool: objectCreator], @"objectCreator",
+          acls = [NSMutableDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithBool: objectCreator], @"objectCreator",
                                    [NSNumber numberWithBool: objectEraser], @"objectEraser", nil];
           [calendar setObject: acls  forKey: @"acls"];
 
