diff --git a/bob/bio/face/config/database/atnt.py b/bob/bio/face/config/database/atnt.py
index 95c38b30a40adf296faa5a92f411289d8193152e..82e9c5e8a40d616089b853d8b971da7a7638a240 100644
--- a/bob/bio/face/config/database/atnt.py
+++ b/bob/bio/face/config/database/atnt.py
@@ -6,4 +6,5 @@ atnt_directory = "[YOUR_ATNT_DIRECTORY]"
 
 database = AtntBioDatabase(
     original_directory=atnt_directory,
+    original_extension=".pgm",
 )