diff --git a/neo4j_arrow/_client.py b/neo4j_arrow/_client.py
index 8f35dc8..6cee9d9 100644
--- a/neo4j_arrow/_client.py
+++ b/neo4j_arrow/_client.py
@@ -100,9 +100,9 @@ def _send_action(self, action: str, body: Dict[str, Any]) -> Dict[str, Any]:
             raise e
 
     @classmethod
-    def _nop(*args, **kwargs):
+    def _nop(cls, data: Arrow) -> Arrow:
         """Used as a no-op mapping function."""
-        pass
+        return data
 
     @classmethod
     def _node_mapper(cls, model: Graph, source_field: Optional[str] = None):
diff --git a/neo4j_arrow/test_client.py b/neo4j_arrow/test_client.py
index c8add40..61db83b 100644
--- a/neo4j_arrow/test_client.py
+++ b/neo4j_arrow/test_client.py
@@ -4,6 +4,15 @@
 import pyarrow as pa
 
 
+def test_nop_mapper():
+    mapper = Neo4jArrowClient._nop
+    t = pa.table({"labels": ["Junk"], "nodeId": ["junk_id"]})
+    result = mapper(t)
+    assert result is not None
+    assert "nodeId" in result.schema.names
+    assert "labels" in result.schema.names
+
+
 def test_node_mapper():
     SRC_KEY = "gcs_source"
     g = Graph(name="junk", nodes=[Node(source="gs://.*/junk.*parquet",