diff --git a/perception_dataset/t4_dataset/classes/abstract_class.py b/perception_dataset/t4_dataset/classes/abstract_class.py
index 6eb762f4..5cd2b44e 100644
--- a/perception_dataset/t4_dataset/classes/abstract_class.py
+++ b/perception_dataset/t4_dataset/classes/abstract_class.py
@@ -81,4 +81,4 @@ def save_json(self, output_dir: str):
     @classmethod
     @abstractmethod
     def from_json(cls, filepath: str):
-        raise NotImplementedError
+        raise NotImplementedError()
diff --git a/tests/t4_dataset/classes/test_abstract_class.py b/tests/t4_dataset/classes/test_abstract_class.py
index 10d58aa9..8721285b 100644
--- a/tests/t4_dataset/classes/test_abstract_class.py
+++ b/tests/t4_dataset/classes/test_abstract_class.py
@@ -26,6 +26,10 @@ def __init__(self):
     def _to_record(self, **kwargs) -> str:
         return AbstractRecordForTest()
 
+    @classmethod
+    def from_json(cls, filepath: str):
+        return AbstractTableForTest()
+
 
 class TestAbstractRecord:
     def test_token(self):