diff --git a/addons/hr_timesheet/models/project.py b/addons/hr_timesheet/models/project.py
index c48360942a6..2a4dbca2fae 100644
--- a/addons/hr_timesheet/models/project.py
+++ b/addons/hr_timesheet/models/project.py
@@ -154,10 +154,10 @@ class Project(models.Model):
             # Timesheets may be stored in a different unit of measure, so first
             # we convert all of them to the reference unit
             # if the timesheet has no product_uom_id then we take the one of the project
-            total_time = sum([
-                unit_amount * uoms_dict.get(product_uom_id, project.timesheet_encode_uom_id).factor_inv
-                for product_uom_id, unit_amount in timesheet_time_dict[project.id]
-            ], 0.0)
+            total_time = 0.0
+            for product_uom_id, unit_amount in timesheet_time_dict[project.id]:
+                factor = uoms_dict.get(product_uom_id, project.timesheet_encode_uom_id).factor_inv
+                total_time += unit_amount * (1.0 if project.encode_uom_in_days else factor)
             # Now convert to the proper unit of measure set in the settings
             total_time *= project.timesheet_encode_uom_id.factor
             project.total_timesheet_time = int(round(total_time))
diff --git a/addons/hr_timesheet/tests/test_timesheet.py b/addons/hr_timesheet/tests/test_timesheet.py
index c4347daace0..575fbee3c1b 100644
--- a/addons/hr_timesheet/tests/test_timesheet.py
+++ b/addons/hr_timesheet/tests/test_timesheet.py
@@ -564,3 +564,27 @@ class TestTimesheet(TestCommonTimesheet):
             'unit_amount': 3,
         })
         self.assertEqual(timesheet.employee_id, self.empl_employee)
+
+    def test_uom_change_timesheet(self):
+        """
+        We check that we don't over transform the timesheet unit amount when changing
+        the company encoding timesheet uom, we keep it in the project as hours.
+        So it will be transformed only once when encoding the timesheet.
+        """
+        Timesheet = self.env['account.analytic.line']
+        project = self.env['project.project'].create({
+            'name': 'Project',
+            'allow_timesheets': True,
+            'partner_id': self.partner.id,
+        })
+        project.allocated_hours = 40.0
+
+        Timesheet.create({
+            'name': 'FirstTimeSheet',
+            'project_id': project.id,
+            'unit_amount': 8,
+            'employee_id': self.empl_employee2.id
+        })
+        self.env.company.timesheet_encode_uom_id = self.env.ref('uom.product_uom_day')
+        self.assertEqual(project.total_timesheet_time, 8, "Total timesheet time should be 8 hours")
+        self.assertEqual(project.timesheet_encode_uom_id.name, 'Days', "Timesheet encode uom should be 'Days'")