diff --git a/ProcessLib/Utils/InitShapeMatrices.h b/ProcessLib/Utils/InitShapeMatrices.h
index 08e1f06d5226af793ea2ab623a3de16f7c65d907..62362c5c2d8573eb8f943374df4ab4e96d46792b 100644
--- a/ProcessLib/Utils/InitShapeMatrices.h
+++ b/ProcessLib/Utils/InitShapeMatrices.h
@@ -32,10 +32,10 @@ initShapeMatrices(MeshLib::Element const& e, unsigned integration_order)
     FemType fe(*static_cast<const typename ShapeFunction::MeshElement*>(&e));
 
     IntegrationMethod integration_method(integration_order);
-    std::size_t const n_integration_points = integration_method.getNumberOfPoints();
+    unsigned const n_integration_points = integration_method.getNumberOfPoints();
 
     shape_matrices.reserve(n_integration_points);
-    for (std::size_t ip = 0; ip < n_integration_points; ++ip) {
+    for (unsigned ip = 0; ip < n_integration_points; ++ip) {
         shape_matrices.emplace_back(ShapeFunction::DIM, GlobalDim,
                                      ShapeFunction::NPOINTS);
         fe.computeShapeFunctions(