diff --git a/tests/test_pretask_check.py b/tests/test_pretask_check.py
index e9f77bae5622cdb0786680fea3b6cf93f76ddf82..e5b82bdebc2a2e05b8a3512d40657b5a866cfb8d 100644
--- a/tests/test_pretask_check.py
+++ b/tests/test_pretask_check.py
@@ -25,6 +25,7 @@ class PretaskWriteCheckTest(AbstractFWorkerTest):
 
     def test_write_file_exists(self):
         def post_run():
+            existing.chmod(0o777)
             self.assertTrue(existing.exists(), '%s should not have been deleted' % existing)
 
         with self.write_check(post_run) as tdir: