diff --git a/ortools/graph/python/linear_sum_assignment.cc b/ortools/graph/python/linear_sum_assignment.cc
index e821ba350d..8b6c662b7b 100644
--- a/ortools/graph/python/linear_sum_assignment.cc
+++ b/ortools/graph/python/linear_sum_assignment.cc
@@ -20,7 +20,7 @@ using ::operations_research::SimpleLinearSumAssignment;
 using NodeIndex = ::operations_research::SimpleLinearSumAssignment::NodeIndex;
 using ::pybind11::arg;
 
-PYBIND11_MODULE(linear_sum_assignment, m) {
+PYBIND11_MODULE(linear_sum_assignment, m, pybind11::mod_gil_not_used()) {
   pybind11::class_<SimpleLinearSumAssignment> slsa(m,
                                                    "SimpleLinearSumAssignment");
   slsa.def(pybind11::init<>());
diff --git a/ortools/graph/python/max_flow.cc b/ortools/graph/python/max_flow.cc
index b9c04cebac..947b9d9eef 100644
--- a/ortools/graph/python/max_flow.cc
+++ b/ortools/graph/python/max_flow.cc
@@ -22,7 +22,7 @@
 using ::operations_research::SimpleMaxFlow;
 using ::pybind11::arg;
 
-PYBIND11_MODULE(max_flow, m) {
+PYBIND11_MODULE(max_flow, m, pybind11::mod_gil_not_used()) {
   pybind11::class_<SimpleMaxFlow> smf(m, "SimpleMaxFlow");
   smf.def(pybind11::init<>());
   smf.def("add_arc_with_capacity", &SimpleMaxFlow::AddArcWithCapacity,
diff --git a/ortools/graph/python/min_cost_flow.cc b/ortools/graph/python/min_cost_flow.cc
index d297ea9930..8e03f6c1aa 100644
--- a/ortools/graph/python/min_cost_flow.cc
+++ b/ortools/graph/python/min_cost_flow.cc
@@ -21,7 +21,7 @@ using ::operations_research::MinCostFlowBase;
 using ::operations_research::SimpleMinCostFlow;
 using ::pybind11::arg;
 
-PYBIND11_MODULE(min_cost_flow, m) {
+PYBIND11_MODULE(min_cost_flow, m, pybind11::mod_gil_not_used()) {
   pybind11::class_<SimpleMinCostFlow> smcf(m, "SimpleMinCostFlow");
   smcf.def(pybind11::init<>());
   smcf.def("add_arc_with_capacity_and_unit_cost",