diff --git a/runbot/models/commit.py b/runbot/models/commit.py
index 02973cfd3..255bb44f3 100644
--- a/runbot/models/commit.py
+++ b/runbot/models/commit.py
@@ -103,7 +103,7 @@ def _export(self, build):
         """Export a git repo into a sources"""
         #  TODO add automated tests
         self.ensure_one()
-        self.repo_id._fetch(self.name)
+        self.repo_id._fetch(self.tree_hash)
         if not self.env['runbot.commit.export'].search([('build_id', '=', build.id), ('commit_id', '=', self.id)]):
             self.env['runbot.commit.export'].create({'commit_id': self.id, 'build_id': build.id})
         export_path = self._source_path()