diff --git a/raillabel_providerkit/validation/validate_schema/validate_schema.py b/raillabel_providerkit/validation/validate_schema/validate_schema.py
index c9f8570..c3320a4 100644
--- a/raillabel_providerkit/validation/validate_schema/validate_schema.py
+++ b/raillabel_providerkit/validation/validate_schema/validate_schema.py
@@ -24,6 +24,8 @@ def _make_errors_readable(errors: ValidationError) -> list[str]:
     for error in json.loads(errors.json()):
         if error["type"] == "missing":
             readable_errors.append(_convert_missing_error_to_string(error))
+        elif error["type"] == "extra_forbidden":
+            readable_errors.append(_convert_unexpected_field_error_to_string(error))
         else:
             raise ValueError
 
@@ -34,6 +36,10 @@ def _convert_missing_error_to_string(error: dict) -> str:
     return f"{_build_error_path(error["loc"][:-1])}: required field '{error["loc"][-1]}' is missing."
 
 
+def _convert_unexpected_field_error_to_string(error: dict) -> str:
+    return f"{_build_error_path(error["loc"][:-1])}: found unexpected field '{error["loc"][-1]}'."
+
+
 def _build_error_path(loc: list[str]) -> str:
     path = "$"
     for part in loc:
diff --git a/tests/test_raillabel_providerkit/validation/validate_schema/test_validate_schema.py b/tests/test_raillabel_providerkit/validation/validate_schema/test_validate_schema.py
index 10a113f..ab65ccb 100644
--- a/tests/test_raillabel_providerkit/validation/validate_schema/test_validate_schema.py
+++ b/tests/test_raillabel_providerkit/validation/validate_schema/test_validate_schema.py
@@ -24,5 +24,15 @@ def test_required_field_missing():
     assert "missing" in actual[0]
 
 
+def test_unsupported_field():
+    data = {"openlabel": {"metadata": {"schema_version": "1.0.0"}, "UNSUPPORTED_FIELD": {}}}
+
+    actual = validate_schema(data)
+    assert len(actual) == 1
+    assert "$.openlabel" in actual[0]
+    assert "unexpected" in actual[0]
+    assert "UNSUPPORTED_FIELD" in actual[0]
+
+
 if __name__ == "__main__":
     pytest.main([__file__, "-v"])