diff --git a/bob/pad/base/test/test_databases.py b/bob/pad/base/test/test_databases.py
index 3653eb5a9ccdfbf58670cc9641de32e250ae662d..703c98703909b9f8ba2c3b35e9b319b1bbfb25f6 100644
--- a/bob/pad/base/test/test_databases.py
+++ b/bob/pad/base/test/test_databases.py
@@ -43,6 +43,10 @@ class DummyDatabaseSqlTest(unittest.TestCase):
         check_file(db.training_files(), 2)
         check_file(db.files([1]))
         check_file(db.reverse(["test/path"]))
+        # check if flat returns flat files
+        assert len(db.all_files(flat=True)) == 2, db.all_files(flat=True)
+        check_file(db.all_files(flat=True)[0:1])
+        check_file(db.all_files(flat=True)[1:2])
 
         file = db.objects()[0]
         assert db.original_file_name(file) == "original/directory/test/path.orig"