diff --git a/biscuit/apps/alsijil/models.py b/biscuit/apps/alsijil/models.py
index fba3ece6792d56d518a4241b97b145d3bb0adae9..5cfa206560a4171a108eba9681d32c25126aeee9 100644
--- a/biscuit/apps/alsijil/models.py
+++ b/biscuit/apps/alsijil/models.py
@@ -25,8 +25,8 @@ class LessonDocumentation(SchoolRelated):
     week = models.IntegerField()
     lesson_period = models.ForeigbKey('chronos.LessonPeriod', models.CASCADE)
 
-    topic = models.CharField(verbose_name=_('Lesson topic'), max_length=200)
-    homework = models.CharField(verbose_name=_('Homework'), max_length=200)
+    topic = models.CharField(verbose_name=_('Lesson topic'), max_length=200, blank=True)
+    homework = models.CharField(verbose_name=_('Homework'), max_length=200, blank=True)
 
     class Meta:
         unique_together = [['school', 'lesson_period', 'week']]