diff --git a/src/phenopacket_mapper/data_standards/data_model.py b/src/phenopacket_mapper/data_standards/data_model.py
index 242f6aa..6f7cddd 100644
--- a/src/phenopacket_mapper/data_standards/data_model.py
+++ b/src/phenopacket_mapper/data_standards/data_model.py
@@ -66,6 +66,9 @@ def __post_init__(self):
             from phenopacket_mapper.utils import str_to_valid_id
             object.__setattr__(self, 'id', str_to_valid_id(self.name))
 
+        if self.required:
+            object.__setattr__(self, 'cardinality', Cardinality(min=1, max=self.cardinality.max))
+
         if isinstance(self.specification, type):
             object.__setattr__(self, 'specification', ValueSet(elements=[self.specification]))
         if isinstance(self.specification, list):
@@ -111,6 +114,8 @@ def __post_init__(self):
             from phenopacket_mapper.utils import str_to_valid_id
             object.__setattr__(self, 'id', str_to_valid_id(self.name))
 
+        if self.required:
+            object.__setattr__(self, 'cardinality', Cardinality(min=1, max=self.cardinality.max))
 
     def __str__(self):
         ret = "DataSection(\n"
@@ -527,6 +532,8 @@ def __post_init__(self):
             from phenopacket_mapper.utils import str_to_valid_id
             object.__setattr__(self, 'id', str_to_valid_id(self.name))
 
+        if self.required:
+            object.__setattr__(self, 'cardinality', Cardinality(min=1, max=self.cardinality.max))
 
 
     def __str__(self):