diff --git a/addons/account/models/account_move_line.py b/addons/account/models/account_move_line.py
index e95879fb585..ea58820bc32 100644
--- a/addons/account/models/account_move_line.py
+++ b/addons/account/models/account_move_line.py
@@ -909,7 +909,7 @@ class AccountMoveLine(models.Model):
             else:
                 line.tax_key = frozendict({'id': line.id})
 
-    @api.depends('tax_ids', 'currency_id', 'partner_id', 'analytic_distribution', 'balance', 'partner_id', 'move_id.partner_id', 'price_unit')
+    @api.depends('tax_ids', 'currency_id', 'partner_id', 'analytic_distribution', 'balance', 'partner_id', 'move_id.partner_id', 'price_unit', 'quantity')
     def _compute_all_tax(self):
         for line in self:
             sign = line.move_id.direction_sign
diff --git a/addons/account/tests/test_invoice_taxes.py b/addons/account/tests/test_invoice_taxes.py
index d6b5cdd09bb..8fd81022461 100644
--- a/addons/account/tests/test_invoice_taxes.py
+++ b/addons/account/tests/test_invoice_taxes.py
@@ -715,3 +715,22 @@ class TestInvoiceTaxes(AccountTestInvoicingCommon):
         self.assertRecordValues(invoice.line_ids.filtered(lambda l: l.account_id.account_type == 'asset_receivable'), [{
             'balance': 686.54,
         }])
+
+    def test_fixed_tax_with_zero_price(self):
+        fixed_tax = self.env['account.tax'].create({
+            'name': 'Test 5 fixed',
+            'amount_type': 'fixed',
+            'amount': 5,
+        })
+        invoice = self._create_invoice([
+            (0, fixed_tax),
+        ])
+        self.assertRecordValues(invoice.line_ids.filtered('tax_line_id'), [{
+            'credit': 5.0,
+            'debit': 0,
+        }])
+        invoice.invoice_line_ids.quantity = 2
+        self.assertRecordValues(invoice.line_ids.filtered('tax_line_id'), [{
+            'credit': 10.0,
+            'debit': 0,
+        }])