diff --git a/src/nomad_simulations/schema_packages/workflow/single_point.py b/src/nomad_simulations/schema_packages/workflow/single_point.py
index 15592046..2a24b8f4 100644
--- a/src/nomad_simulations/schema_packages/workflow/single_point.py
+++ b/src/nomad_simulations/schema_packages/workflow/single_point.py
@@ -106,7 +106,7 @@ def normalize(self, archive: 'EntryArchive', logger: 'BoundLogger') -> None:
         # SinglePoint can only have one task; if it has more, delete the `tasks`
         if self.tasks is not None and len(self.tasks) > 1:
             logger.error('A `SinglePoint` workflow must have only one task.')
-            self.tasks = None
+            self.tasks: list[Task] = []
             return
 
         # Generate the `tasks` section if this does not exist