diff --git a/runbot/models/repo.py b/runbot/models/repo.py
index b8361609..e2659121 100644
--- a/runbot/models/repo.py
+++ b/runbot/models/repo.py
@@ -561,7 +561,7 @@ class Repo(models.Model):
         for addons_path in (self.addons_paths or '').split(','):
             base_path = f'{self.name}/{addons_path}'
             if file.startswith(base_path):
-                return file.replace(base_path, '').strip('/').split('/')[0]
+                return file[len(base_path):].strip('/').split('/')[0]
 
 
 class RefTime(models.Model):
diff --git a/runbot/tests/test_build_config_step.py b/runbot/tests/test_build_config_step.py
index 702eacba..1053a098 100644
--- a/runbot/tests/test_build_config_step.py
+++ b/runbot/tests/test_build_config_step.py
@@ -108,7 +108,9 @@ class TestCodeowner(TestBuildConfigStepCommon):
         self.assertEqual(self.repo_server.addons_paths, 'addons,core/addons')
         self.assertEqual('module1', self.repo_server._get_module('server/core/addons/module1/some/file.py'))
         self.assertEqual('module1', self.repo_server._get_module('server/addons/module1/some/file.py'))
+        self.assertEqual('module_addons', self.repo_addons._get_module('addons/module_addons/some/file.py'))
         self.assertEqual(None, self.repo_server._get_module('server/core/module1/some/file.py'))
+        self.assertEqual(None, self.repo_server._get_module('server/core/module/some/file.py'))
 
     def test_codeowner_regex_multiple(self):
         self.diff = 'file.js\nfile.py\nfile.xml'