diff --git a/flax/nnx/object.py b/flax/nnx/object.py
index b8f35ba752..0c8c60601f 100644
--- a/flax/nnx/object.py
+++ b/flax/nnx/object.py
@@ -16,6 +16,7 @@
 
 import dataclasses
 import inspect
+import sys
 import threading
 import typing as tp
 from abc import ABCMeta
@@ -157,7 +158,9 @@ def __init_subclass__(cls) -> None:
       init=cls._graph_node_init,  # type: ignore
     )
 
-    cls.__signature__ = inspect.signature(cls.__init__)
+    if 'sphinx-build' in sys.argv[0]:
+      # set correct signature for sphinx
+      cls.__signature__ = inspect.signature(cls.__init__)
 
   if not tp.TYPE_CHECKING: