diff --git a/python_binding/operator/pybind_Operator.cpp b/python_binding/operator/pybind_Operator.cpp
index 2b2f30f14931fd041bfb4ec1a712e5c9419fdf22..dbf71a3cad870d848fbc2f5f67c13d5347b38b89 100644
--- a/python_binding/operator/pybind_Operator.cpp
+++ b/python_binding/operator/pybind_Operator.cpp
@@ -37,7 +37,7 @@ void init_Operator(py::module& m){
     py::class_<Operator, std::shared_ptr<Operator>>(m, "Operator")
     .def("__repr__", &Operator::repr)
     .def("backend", &Operator::backend)
-    .def("set_output", py::overload_cast<const IOIndex_t, const std::shared_ptr<Data>&>(&Operator::setOutput), py::arg("outputIdx"), py::arg("data"))
+    .def("set_output", py::overload_cast<const IOIndex_t, const std::shared_ptr<Data>&>(&Operator::setOutput, py::const_), py::arg("outputIdx"), py::arg("data"))
     .def("set_input", py::overload_cast<const IOIndex_t, const std::shared_ptr<Data>&>(&Operator::setInput), py::arg("inputIdx"), py::arg("data"))
     .def("get_raw_output", &Operator::getRawOutput, py::arg("outputIdx"))
     .def("set_input", py::overload_cast<const IOIndex_t, const std::shared_ptr<Data>&>(&Operator::setInput), py::arg("inputIdx"), py::arg("data"))
diff --git a/python_binding/operator/pybind_OperatorTensor.cpp b/python_binding/operator/pybind_OperatorTensor.cpp
index 4d4541ab36468bc6b531e0242888dd70c5afc71f..8c515e321207605c20acc9e5b02271906c9707d1 100644
--- a/python_binding/operator/pybind_OperatorTensor.cpp
+++ b/python_binding/operator/pybind_OperatorTensor.cpp
@@ -28,7 +28,7 @@ void init_OperatorTensor(py::module& m){
     .def("get_output", &OperatorTensor::getOutput, py::arg("outputIdx"))
     .def("get_input", &OperatorTensor::getInput, py::arg("inputIdx"))
 
-    .def("set_output", (void (OperatorTensor::*)(const IOIndex_t, const std::shared_ptr<Data>&)) &OperatorTensor::setOutput, py::arg("outputIdx"), py::arg("data"))
+    .def("set_output", (void (OperatorTensor::*)(const IOIndex_t, const std::shared_ptr<Data>&) const) &OperatorTensor::setOutput, py::arg("outputIdx"), py::arg("data"))
     .def("set_input", (void (OperatorTensor::*)(const IOIndex_t, const std::shared_ptr<Data>&)) &OperatorTensor::setInput, py::arg("outputIdx"), py::arg("data"))
     .def("forward_dims", &OperatorTensor::forwardDims, py::arg("allow_data_dependency") = false)
     .def("dims_forwarded", &OperatorTensor::dimsForwarded)