diff --git a/contract/models/contract_line.py b/contract/models/contract_line.py
index 3494b0b2..460990a2 100644
--- a/contract/models/contract_line.py
+++ b/contract/models/contract_line.py
@@ -946,3 +946,12 @@ class AccountAnalyticInvoiceLine(models.Model):
         return super(AccountAnalyticInvoiceLine, self).fields_view_get(
             view_id, view_type, toolbar, submenu
         )
+
+    @api.multi
+    def unlink(self):
+        """stop unlink uncnacled lines"""
+        if not all(self.mapped('is_canceled')):
+            raise ValidationError(
+                _("Contract line must be canceled before delete")
+            )
+        return super(AccountAnalyticInvoiceLine, self).unlink()
diff --git a/contract/tests/test_contract.py b/contract/tests/test_contract.py
index 57abfd75..8843ddcc 100644
--- a/contract/tests/test_contract.py
+++ b/contract/tests/test_contract.py
@@ -431,7 +431,7 @@ class TestContract(TestContractBase):
 
     def test_onchange_contract_template_id_lines(self):
         """It should create invoice lines for the contract lines."""
-
+        self.acct_line.cancel()
         self.acct_line.unlink()
         self.contract.contract_template_id = self.template
 
@@ -1370,3 +1370,7 @@ class TestContract(TestContractBase):
         first, last = self.acct_line._get_invoiced_period()
         self.assertEqual(first, to_date('2020-01-05'))
         self.assertEqual(last, to_date('2020-03-15'))
+
+    def test_unlink(self):
+        with self.assertRaises(ValidationError):
+            self.acct_line.unlink()