diff --git a/book.py b/book.py
index bbeb106..53e1d56 100644
--- a/book.py
+++ b/book.py
@@ -289,8 +289,12 @@ class Book(tree(separator='/'), Workflow, ModelSQL, ModelView):
                     ], query=True)),
             ]
         if date_limit == True:
+            dt1 = context.get('date', None)
+            dt2 = IrDate.today()
+            if not isinstance(dt1, type(dt2)):
+                dt1 = dt2
             query.append(
-                    ('date', '<=', context.get('date', IrDate.today()))
+                    ('date', '<=', dt1)
                 )
         line_query = Line.search(query, query=True)