diff --git a/src/fmu/dataio/_products/inplace_volumes.py b/src/fmu/dataio/_products/inplace_volumes.py
index f3acf4350..f7b5c4828 100644
--- a/src/fmu/dataio/_products/inplace_volumes.py
+++ b/src/fmu/dataio/_products/inplace_volumes.py
@@ -34,7 +34,7 @@ class InplaceVolumesResultRow(BaseModel):
     BULK: float = Field(ge=0.0)
     NET: Optional[float] = Field(default=None, ge=0.0)
     PORV: float = Field(ge=0.0)
-    HCPV: Optional[float] = Field(default=None, ge=0.0)
+    HCPV: float = Field(ge=0.0)
     STOIIP: Optional[float] = Field(default=None, ge=0.0)
     GIIP: Optional[float] = Field(default=None, ge=0.0)
     ASSOCIATEDGAS: Optional[float] = Field(default=None, ge=0.0)
diff --git a/tests/test_export_rms/test_export_rms_volumetrics.py b/tests/test_export_rms/test_export_rms_volumetrics.py
index 9460ba412..f38a1b3c1 100644
--- a/tests/test_export_rms/test_export_rms_volumetrics.py
+++ b/tests/test_export_rms/test_export_rms_volumetrics.py
@@ -377,10 +377,9 @@ def test_inplace_volumes_export_and_result_columns_are_the_same(
     )
 
 
-def test_that_required_columns_one_to_one_in_enum_and_schema() -> None:
-    schema_required_fields = [
-        name
-        for name, field in InplaceVolumesResultRow.__fields__.items()
-        if field.required
-    ]
-    assert _enums.InplaceVolumes.required_columns == schema_required_fields
+def test_that_required_columns_one_to_one_in_enums_and_schema() -> None:
+    schema_required_fields = []
+    for field_name, field_info in InplaceVolumesResultRow.model_fields.items():
+        if field_info.is_required():
+            schema_required_fields.append(field_name)
+    assert _enums.InplaceVolumes.required_columns() == schema_required_fields