diff --git a/src/videoag_common/objects/course.py b/src/videoag_common/objects/course.py
index d5611c6637cb3bc6c5a4bc924133579ddb529cd1..746c5b01942563b0c44422dbbe7c6679b4e54a12 100644
--- a/src/videoag_common/objects/course.py
+++ b/src/videoag_common/objects/course.py
@@ -404,7 +404,7 @@ class Course(DeletableApiObject, VisibilityApiObject, ApiViewPermissionsObject,
         )
     )
     authentication_information: Mapped[str] = api_mapped(
-        mapped_column(Text(collation=STRING_COLLATION), nullable=True, default=None),
+        mapped_column(Text(collation=STRING_COLLATION), nullable=False, default=""),
         ApiStringField(
             max_length=8192,
             include_in_config=True,