diff --git a/ProcessLib/BoundaryCondition/Python/BHEInflowPythonBoundaryCondition.h b/ProcessLib/BoundaryCondition/Python/BHEInflowPythonBoundaryCondition.h
index 57ed204bf26160b0873e4ea4000b0812b1f946e5..c5541c88a7b6d1b5e8254cc74a3c286faf15c905 100644
--- a/ProcessLib/BoundaryCondition/Python/BHEInflowPythonBoundaryCondition.h
+++ b/ProcessLib/BoundaryCondition/Python/BHEInflowPythonBoundaryCondition.h
@@ -41,7 +41,7 @@ public:
           _bhe(bhe),
           _py_bc_object(py_bc_object)
     {
-        const auto g_idx_T_out = in_out_global_indices.second;
+        const auto g_idx_T_out = static_cast<int>(in_out_global_indices.second);
 
         // store the bc node ids to BHE network dataframe
         std::get<3>(_py_bc_object.dataframe_network).emplace_back(g_idx_T_out);