diff --git a/timesheet.py b/timesheet.py
index 1283d3d608..2e5e0553a2 100644
--- a/timesheet.py
+++ b/timesheet.py
@@ -30,6 +30,6 @@ class TimesheetLine:
 
     @classmethod
     def delete(cls, records):
-        if any(r.timesheet_line for r in records):
+        if any(r.invoice_line for r in records):
             cls.raise_user_error('delete_invoiced_line')
         super(TimesheetLine, cls).delete(records)