diff --git a/test/validation_test.py b/test/validation_test.py
index 8dae133..e6c31c7 100644
--- a/test/validation_test.py
+++ b/test/validation_test.py
@@ -219,5 +219,31 @@ def test_validation_timeseries():
         schema_type="plant/energy_resource",
     )
 
+def test_restrictive_rejects_additional_properties_in_ref_schemas():
+    """Test that restrictive validation catches additional properties in $ref-resolved schemas.
+
+    The site schema is loaded via $ref from wind_energy_system.yaml.
+    Without the fix to propagate enforcement through the registry,
+    extra properties in $ref-resolved schemas would pass silently.
+    """
+    plant_reference_path = Path(windIO.plant_ex.__file__).parent
+    data = windIO.load_yaml(
+        plant_reference_path / "wind_energy_system/IEA37_case_study_1_2_wind_energy_system.yaml"
+    )
+
+    # Inject an extra property into site, which is resolved via $ref
+    data["site"]["not_in_schema"] = "should be rejected"
+
+    # restrictive=True (default) must reject it
+    with pytest.raises(
+        jsonschema.exceptions.ValidationError,
+        match="Additional properties are not allowed.*'not_in_schema'",
+    ):
+        windIO.validate(data, "plant/wind_energy_system", restrictive=True)
+
+    # restrictive=False must allow it
+    windIO.validate(data, "plant/wind_energy_system", restrictive=False)
+
+
 if __name__ == "__main__":
     test_validate_raise()
\ No newline at end of file
diff --git a/windIO/validator.py b/windIO/validator.py
index eec6b95..746067d 100644
--- a/windIO/validator.py
+++ b/windIO/validator.py
@@ -11,16 +11,20 @@
 from .schemas import schemaPath, schema_validation_error_formatter
 
 
-def retrieve_yaml(uri: str):
-    if not uri.endswith(".yaml"):
-        raise NoSuchResource(ref=uri)
-    uri = uri.removeprefix("windIO/")
-    path = schemaPath / Path(uri)
-    contents = load_yaml(path)
-    return Resource.from_contents(contents)
+def _make_retrieve(restrictive=False):
+    def retrieve(uri: str):
+        if not uri.endswith(".yaml"):
+            raise NoSuchResource(ref=uri)
+        uri = uri.removeprefix("windIO/")
+        path = schemaPath / Path(uri)
+        contents = load_yaml(path)
+        if restrictive:
+            _enforce_no_additional_properties(contents)
+        return Resource.from_contents(contents)
+    return retrieve
 
 
-registry = Registry(retrieve=retrieve_yaml)
+registry = Registry(retrieve=_make_retrieve())
 
 
 def _enforce_no_additional_properties(schema):
@@ -93,11 +97,14 @@ def validate(
     schema = load_yaml(schema_file)
     if restrictive:
         schema = _enforce_no_additional_properties(schema)
+        reg = Registry(retrieve=_make_retrieve(restrictive=True))
+    else:
+        reg = registry
 
     if defaults:
-        _jsonschema_validate_modified(data, schema, cls = DefaultValidatingDraft7Validator, registry=registry)
+        _jsonschema_validate_modified(data, schema, cls = DefaultValidatingDraft7Validator, registry=reg)
     else:
-        _jsonschema_validate_modified(data, schema, registry=registry)
+        _jsonschema_validate_modified(data, schema, registry=reg)
 
     return data