diff --git a/docs_nnx/conf.py b/docs_nnx/conf.py
index 7eee4706..6bfd9704 100644
--- a/docs_nnx/conf.py
+++ b/docs_nnx/conf.py
@@ -35,6 +35,8 @@
 sys.path.insert(0, os.path.abspath('..'))
 # Include local extension.
 sys.path.append(os.path.abspath('./_ext'))
+# Set environment variable to indicate that we are building the docs.
+os.environ['FLAX_DOC_BUILD'] = 'true'
 
 # patch sphinx
 # -- Project information -----------------------------------------------------
diff --git a/flax/nnx/object.py b/flax/nnx/object.py
index b8f35ba7..e88786b7 100644
--- a/flax/nnx/object.py
+++ b/flax/nnx/object.py
@@ -16,6 +16,7 @@
 
 import dataclasses
 import inspect
+import os
 import threading
 import typing as tp
 from abc import ABCMeta
@@ -38,6 +39,7 @@
 
 G = tp.TypeVar('G', bound='Object')
 
+BUILDING_DOCS = 'FLAX_DOC_BUILD' in os.environ
 
 def _collect_stats(
   node: tp.Any, node_stats: dict[int, dict[type[Variable], SizeBytes]]
@@ -157,7 +159,9 @@ def __init_subclass__(cls) -> None:
       init=cls._graph_node_init,  # type: ignore
     )
 
-    cls.__signature__ = inspect.signature(cls.__init__)
+    if BUILDING_DOCS:
+      # set correct signature for sphinx
+      cls.__signature__ = inspect.signature(cls.__init__)
 
   if not tp.TYPE_CHECKING: