diff --git a/ProcessLib/BoundaryCondition/NonuniformNeumannBoundaryCondition.cpp b/ProcessLib/BoundaryCondition/NonuniformNeumannBoundaryCondition.cpp
index cddd884a62616018bc9fc5a3706eda7cb9a6da8b..0e996dfed119b499646259cb93c41ffdb561b896 100644
--- a/ProcessLib/BoundaryCondition/NonuniformNeumannBoundaryCondition.cpp
+++ b/ProcessLib/BoundaryCondition/NonuniformNeumannBoundaryCondition.cpp
@@ -67,7 +67,7 @@ createNonuniformNeumannBoundaryCondition(
 
     std::string mapping_to_bulk_nodes_property = "OriginalSubsurfaceNodeIDs";
     auto const* const mapping_to_bulk_nodes =
-        boundary_mesh->getProperties().getPropertyVector<unsigned long>(
+        boundary_mesh->getProperties().getPropertyVector<std::size_t>(
             mapping_to_bulk_nodes_property);
 
     if (!(mapping_to_bulk_nodes &&
diff --git a/ProcessLib/BoundaryCondition/NonuniformNeumannBoundaryConditionLocalAssembler.h b/ProcessLib/BoundaryCondition/NonuniformNeumannBoundaryConditionLocalAssembler.h
index aeaa4f895ac1c80b724412855c6a2304412abf8c..8c34c7580a0ea9669424fb9be846fa3d637456d1 100644
--- a/ProcessLib/BoundaryCondition/NonuniformNeumannBoundaryConditionLocalAssembler.h
+++ b/ProcessLib/BoundaryCondition/NonuniformNeumannBoundaryConditionLocalAssembler.h
@@ -24,7 +24,7 @@ struct NonuniformNeumannBoundaryConditionData
 
     // Used for mapping boundary nodes to bulk nodes.
     std::size_t bulk_mesh_id;
-    MeshLib::PropertyVector<unsigned long> const& mapping_to_bulk_nodes;
+    MeshLib::PropertyVector<std::size_t> const& mapping_to_bulk_nodes;
     NumLib::LocalToGlobalIndexMap const& dof_table_bulk;
     int const variable_id_bulk;
     int const component_id_bulk;
@@ -93,9 +93,8 @@ public:
             auto const bulk_node_id =
                 _data.mapping_to_bulk_nodes.getComponent(i, 0);
 
-            MeshLib::Location const l{_data.bulk_mesh_id,
-                                      MeshLib::MeshItemType::Node,
-                                      static_cast<std::size_t>(bulk_node_id)};
+            MeshLib::Location const l{
+                _data.bulk_mesh_id, MeshLib::MeshItemType::Node, bulk_node_id};
 
             i = _data.dof_table_bulk.getGlobalIndex(l, _data.variable_id_bulk,
                                                     _data.component_id_bulk);