diff --git a/biscuit/apps/chronos/tables.py b/biscuit/apps/chronos/tables.py
index 3e7979925b21b8d8407c36663414395ab46ba4a3..c1a55c4ef47d61e31299e5a43a6ddc206a7bdb26 100644
--- a/biscuit/apps/chronos/tables.py
+++ b/biscuit/apps/chronos/tables.py
@@ -10,7 +10,7 @@ from .models import LessonPeriod
 
 
 def _css_class_from_lesson_state(record: Optional[LessonPeriod] = None, table: Optional[LessonsTable] = None) -> str:
-    if record.get_substitution(table._week):
+    if record.get_substitution(record._week):
         return 'table-warning'
     else:
         return ''