diff --git a/addons/sale_project/models/project.py b/addons/sale_project/models/project.py
index 9b7113a381d..3b12797eb9e 100644
--- a/addons/sale_project/models/project.py
+++ b/addons/sale_project/models/project.py
@@ -496,12 +496,12 @@ class ProjectTask(models.Model):
                 task.partner_id = sale_order_id.partner_id
             task.sale_order_id = sale_order_id
 
-    @api.depends('commercial_partner_id', 'sale_line_id.order_partner_id', 'parent_id.sale_line_id', 'project_id.sale_line_id')
+    @api.depends('commercial_partner_id', 'sale_line_id.order_partner_id', 'parent_id.sale_line_id', 'project_id.sale_line_id', 'milestone_id.sale_line_id')
     def _compute_sale_line(self):
         for task in self:
             if not task.sale_line_id:
                 # if the display_project_id is set then it means the task is classic task or a subtask with another project than its parent.
-                task.sale_line_id = task.display_project_id.sale_line_id or task.parent_id.sale_line_id or task.project_id.sale_line_id
+                task.sale_line_id = task.display_project_id.sale_line_id or task.parent_id.sale_line_id or task.project_id.sale_line_id or task.milestone_id.sale_line_id
             # check sale_line_id and customer are coherent
             if task.sale_line_id.order_partner_id.commercial_partner_id != task.partner_id.commercial_partner_id:
                 task.sale_line_id = False
diff --git a/addons/sale_project/tests/test_so_line_milestones.py b/addons/sale_project/tests/test_so_line_milestones.py
index 8b33b666592..c804e0215e5 100644
--- a/addons/sale_project/tests/test_so_line_milestones.py
+++ b/addons/sale_project/tests/test_so_line_milestones.py
@@ -9,8 +9,8 @@ from odoo.tests.common import tagged
 class TestSoLineMilestones(TestSaleCommon):
 
     @classmethod
-    def setUpClass(cls):
-        super().setUpClass()
+    def setUpClass(cls, chart_template_ref=None):
+        super().setUpClass(chart_template_ref=chart_template_ref)
 
         uom_hour = cls.env.ref('uom.product_uom_hour')
 
@@ -107,3 +107,17 @@ class TestSoLineMilestones(TestSaleCommon):
 
         self.milestone1.unlink()
         self.assertEqual(self.sol1.qty_delivered, 0.0, "Delivered quantity should update when a milestone is removed")
+
+    def test_compute_sale_line_in_task(self):
+        task = self.env['project.task'].create({
+            'name': 'Test Task',
+            'project_id': self.project.id,
+        })
+        self.assertEqual(task.sale_line_id, self.sol1, 'The task should have the one of the project linked')
+        self.project.sale_line_id = False
+        task.sale_line_id = False
+        self.assertFalse(task.sale_line_id)
+        task.write({'milestone_id': self.milestone1.id})
+        self.assertEqual(task.sale_line_id, self.milestone1.sale_line_id, 'The task should have the SOL from the milestone.')
+        self.project.sale_line_id = self.sol2
+        self.assertEqual(task.sale_line_id, self.sol1, 'The task should keep the SOL linked to the milestone.')