diff --git a/modules/cellframe-sdk/chain/src/libdap-chain-python.c b/modules/cellframe-sdk/chain/src/libdap-chain-python.c
index ecc0a4c1ae701a028c87cc78b539e166776cf7b9..e826fa2e3dfd27d36205c13a0e0f3945b9efd27b 100644
--- a/modules/cellframe-sdk/chain/src/libdap-chain-python.c
+++ b/modules/cellframe-sdk/chain/src/libdap-chain-python.c
@@ -375,7 +375,7 @@ PyObject *dap_chain_net_add_atom_notify_callback(PyObject *self, PyObject *args)
     l_callback->arg = obj_arg;
     Py_INCREF(obj_func);
     Py_INCREF(obj_arg);
-    dap_chain_add_callback_notify(l_chain, _wrapping_dap_chain_atom_notify_handler, l_callback);
+    dap_chain_add_callback_notify(l_chain, _wrapping_dap_chain_atom_notify_handler, NULL, l_callback);
     Py_RETURN_NONE;
 }