diff --git a/src/bob/pad/base/pipelines/abstract_classes.py b/src/bob/pad/base/pipelines/abstract_classes.py
index caf249838e9cf975db72989652df971db4b4e862..f0ed71a21fae01d984165ac84003e74340f6693e 100644
--- a/src/bob/pad/base/pipelines/abstract_classes.py
+++ b/src/bob/pad/base/pipelines/abstract_classes.py
@@ -49,5 +49,5 @@ class Database(metaclass=ABCMeta):
             for group in groups:
                 samples.extend(self.predict_samples(group=group))
         else:
-            samples.extend(group=None)
+            samples.extend(self.predict_samples(group=group))
         return samples