diff --git a/tests/test_protected.py b/tests/test_protected.py
new file mode 100644
index 0000000..163ef7a
--- /dev/null
+++ b/tests/test_protected.py
@@ -0,0 +1,15 @@
+import znflow
+
+
+class MyNode(znflow.Node):
+    _protected_ = znflow.Node._protected_ + ["a"]
+
+    a: int = 42
+    b: int = 42
+
+
+def test_protected():
+    with znflow.DiGraph():
+        node = MyNode()
+        assert node.a == 42
+        assert isinstance(node.b, znflow.Connection)
diff --git a/znflow/node.py b/znflow/node.py
index 052991a..015a664 100644
--- a/znflow/node.py
+++ b/znflow/node.py
@@ -70,7 +70,7 @@ def __new__(cls, *args, **kwargs):
             graph.add_node(instance, this_uuid=this_uuid)
         return instance
 
-    def __getattribute__(self, item):
+    def __getattribute__(self, item: str):
         if item.startswith("_"):
             return super().__getattribute__(item)
         if self._graph_ not in [empty_graph, None]:
@@ -80,7 +80,7 @@ def __getattribute__(self, item):
                         f"'{self.__class__.__name__}' object has no attribute '{item}'"
                     )
 
-            if item not in type(self)._protected_:
+            if item not in self._protected_:
                 if self._in_construction:
                     return super().__getattribute__(item)
                 return Connection(instance=self, attribute=item)