diff --git a/src/paveit/datamodels/norm_specification.py b/src/paveit/datamodels/norm_specification.py
index 7beb9ba..2be9627 100644
--- a/src/paveit/datamodels/norm_specification.py
+++ b/src/paveit/datamodels/norm_specification.py
@@ -18,7 +18,7 @@ class EnumerateBase(Document):
 class DeliveryGrain(EnumerateBase):
     name = StringField()
     category = StringField()
-    norm = StringField(required=True, default='TL Gestein-StB 04 (2018)')
+    norm =  EnumField(NormEnum, default=NormEnum.TLGestein2018)
     
 # Bitumen