diff --git a/openupgrade_scripts/scripts/hr_timesheet/18.0.1.1/post-migration.py b/openupgrade_scripts/scripts/hr_timesheet/18.0.1.1/post-migration.py
index d027c997031..1a5232aeeb4 100644
--- a/openupgrade_scripts/scripts/hr_timesheet/18.0.1.1/post-migration.py
+++ b/openupgrade_scripts/scripts/hr_timesheet/18.0.1.1/post-migration.py
@@ -1,8 +1,26 @@
 # Copyright 2025 Le Filament (https://le-filament.com)
+# Copyright 2025 Tecnativa - Pedro M. Baeza
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
 from openupgradelib import openupgrade
 
 
+def _convert_task_progress(env):
+    """On v17, the value was multiplied by 100:
+
+    https://github.com/odoo/odoo/blob/f9726cfe93e8850a38d9de06acfa5d78473b50b0/addons/hr_timesheet/models/project_task.py#L101
+
+    but on v18, it's not:
+
+    https://github.com/odoo/odoo/blob/1cac54db8634267a780b4011291f1e8a80ac5f5b/addons/hr_timesheet/models/project_task.py#L98
+
+    so we have to divide current stored values by 100.
+    """
+    openupgrade.logged_query(
+        env.cr, "UPDATE project_task SET progress = progress / 100"
+    )
+
+
 @openupgrade.migrate()
 def migrate(env, version):
     openupgrade.load_data(env, "hr_timesheet", "18.0.1.1/noupdate_changes.xml")
+    _convert_task_progress(env)