diff --git a/bob/bio/base/database/filelist/query.py b/bob/bio/base/database/filelist/query.py
index 2d6eaf1399d63608f3ea6f49564ee7bf507f23f1..c3454093192d7c54f6eb0f40145b30da76421607 100644
--- a/bob/bio/base/database/filelist/query.py
+++ b/bob/bio/base/database/filelist/query.py
@@ -10,6 +10,9 @@ from .. import BioFile
 
 from .models import ListReader
 
+import logging
+logger = logging.getLogger('bob.bio.base')
+
 
 class FileListBioDatabase(ZTBioDatabase):
     """This class provides a user-friendly interface to databases that are given as file lists.
@@ -226,10 +229,12 @@ class FileListBioDatabase(ZTBioDatabase):
             if group == 'world':
                 continue
             if add_zt_files:
-                if not self.implements_zt(self.protocol, group):
-                    raise ValueError("ZT score files are requested, but no such files are defined in group %s for protocol %s", group, self.protocol)
-                files += self.tobjects(group, self.protocol)
-                files += self.zobjects(group, self.protocol, **self.z_probe_options)
+                if self.implements_zt(self.protocol, group):
+                    files += self.tobjects(group, self.protocol)
+                    files += self.zobjects(group, self.protocol, **self.z_probe_options)
+                else:
+                    logger.warn("ZT score files are requested, but no such files are defined in group %s for protocol %s", group, self.protocol)
+
         return self.sort(self._make_bio(files))
 
 
diff --git a/bob/bio/base/test/test_filelist.py b/bob/bio/base/test/test_filelist.py
index 405591a866ba3e7bc2c630a27b533d2e5a39dbb6..c1c0735b475755e8476b783379ffb568a274640b 100644
--- a/bob/bio/base/test/test_filelist.py
+++ b/bob/bio/base/test/test_filelist.py
@@ -136,6 +136,12 @@ def test_query_protocol():
     assert len(db.objects(protocol=prot, groups='dev', purposes='probe')) == 9
 
 
+def test_noztnorm():
+    db = FileListBioDatabase(os.path.join(os.path.dirname(example_dir),
+                                          'example_filelist2'), 'test')
+    assert len(db.all_files())
+
+
 def test_query_dense():
     db = FileListBioDatabase(example_dir, 'test', use_dense_probe_file_list=True)