diff --git a/MeshGeoToolsLib/AppendLinesAlongPolyline.cpp b/MeshGeoToolsLib/AppendLinesAlongPolyline.cpp
index 24637f64618f610dacbb6fc125e6cc10c74c1050..731173f578025273fcbc4c40fe299fb0faa63a62 100644
--- a/MeshGeoToolsLib/AppendLinesAlongPolyline.cpp
+++ b/MeshGeoToolsLib/AppendLinesAlongPolyline.cpp
@@ -35,9 +35,9 @@ MeshLib::Mesh* appendLinesAlongPolylines(const MeshLib::Mesh &mesh, const GeoLib
 	for (auto e : vec_new_eles)
 		max_matID = std::max(max_matID, e->getValue());
 
-	const size_t n_ply (ply_vec.size());
+	const std::size_t n_ply (ply_vec.size());
 	// for each polyline
-	for (size_t k(0); k < n_ply; k++)
+	for (std::size_t k(0); k < n_ply; k++)
 	{
 		const GeoLib::Polyline* ply = (*ply_vec.getVector())[k];
 
@@ -52,7 +52,7 @@ MeshLib::Mesh* appendLinesAlongPolylines(const MeshLib::Mesh &mesh, const GeoLib
 		}
 
 		// add line elements
-		for (size_t i=0; i<vec_nodes_on_ply.size()-1; i++) {
+		for (std::size_t i=0; i<vec_nodes_on_ply.size()-1; i++) {
 			std::array<MeshLib::Node*, 2> element_nodes;
 			element_nodes[0] = vec_new_nodes[vec_nodes_on_ply[i]];
 			element_nodes[1] = vec_new_nodes[vec_nodes_on_ply[i+1]];
diff --git a/MeshGeoToolsLib/BoundaryElementsOnSurface.cpp b/MeshGeoToolsLib/BoundaryElementsOnSurface.cpp
index 4e3fdd5aca5db410868931273baadb53594434ba..83c154dfb3f3d0eb11b7e09d40d8b578e970772e 100644
--- a/MeshGeoToolsLib/BoundaryElementsOnSurface.cpp
+++ b/MeshGeoToolsLib/BoundaryElementsOnSurface.cpp
@@ -36,8 +36,8 @@ BoundaryElementsOnSurface::BoundaryElementsOnSurface(MeshLib::Mesh const& mesh,
 		for (unsigned i=0; i<e->getNFaces(); i++) {
 			auto* face = e->getFace(i);
 			// check
-			size_t cnt_match = 0;
-			for (size_t j=0; j<face->getNBaseNodes(); j++) {
+			std::size_t cnt_match = 0;
+			for (std::size_t j=0; j<face->getNBaseNodes(); j++) {
 				if (std::find(node_ids_on_sfc.begin(), node_ids_on_sfc.end(), face->getNodeIndex(j)) != node_ids_on_sfc.end())
 					cnt_match++;
 				else
diff --git a/MeshGeoToolsLib/GeoMapper.cpp b/MeshGeoToolsLib/GeoMapper.cpp
index 1963bbcafb911789efcedf78e0d2cbbc1e95587a..3f7914d61ca288c5081de6830c2587247a01ad9c 100644
--- a/MeshGeoToolsLib/GeoMapper.cpp
+++ b/MeshGeoToolsLib/GeoMapper.cpp
@@ -112,7 +112,7 @@ void GeoMapper::mapData()
 		min_val = bounding_box.getMinPoint()[2];
 		max_val = bounding_box.getMaxPoint()[2];
 	}
-	size_t nPoints (points->size());
+	std::size_t nPoints (points->size());
 
 	if (!is_borehole)
 	{
@@ -133,7 +133,7 @@ void GeoMapper::mapData()
 
 			GeoLib::StationBorehole* borehole = static_cast<GeoLib::StationBorehole*>(pnt);
 			const std::vector<GeoLib::Point*> layers = borehole->getProfile();
-			size_t nLayers = layers.size();
+			std::size_t nLayers = layers.size();
 			for (unsigned k=0; k<nLayers; ++k)
 			{
 				GeoLib::Point* layer_pnt = layers[k];
@@ -204,7 +204,7 @@ void GeoMapper::advancedMapOnMesh(const MeshLib::Mesh* mesh, const std::string &
 	// copy geometry (and set z=0 for all points)
 	unsigned nGeoPoints ( points->size() );
 	std::vector<GeoLib::Point*> *new_points = new std::vector<GeoLib::Point*>(nGeoPoints);
-	for (size_t i=0; i<nGeoPoints; ++i)
+	for (std::size_t i=0; i<nGeoPoints; ++i)
 		(*new_points)[i] = new GeoLib::Point((*(*points)[i])[0],(*(*points)[i])[1],0.0);
 	std::vector<GeoLib::Polyline*> *new_lines (copyPolylinesVector(this->_geo_objects.getPolylineVec(this->_geo_name), new_points));
 
@@ -215,7 +215,7 @@ void GeoMapper::advancedMapOnMesh(const MeshLib::Mesh* mesh, const std::string &
 	const unsigned nMeshNodes ( mesh->getNNodes() );
 	std::vector<int> closest_geo_point(nMeshNodes); // index of closest geo point for each mesh node in (x,y)-plane
 	std::vector<double> dist(nMeshNodes);  // distance between geo points and mesh nodes in (x,y)-plane
-	for (size_t i=0; i<nMeshNodes; ++i)
+	for (std::size_t i=0; i<nMeshNodes; ++i)
 	{
 		const double zero_coords[3] = {(* mesh->getNode(i))[0], (* mesh->getNode(i))[1], 0.0};
 		GeoLib::Point* pnt = grid.getNearestPoint(zero_coords);
@@ -224,7 +224,7 @@ void GeoMapper::advancedMapOnMesh(const MeshLib::Mesh* mesh, const std::string &
 	}
 
 	// store for each point the line segment to which it was added.
-	const size_t nLines (new_lines->size());
+	const std::size_t nLines (new_lines->size());
 	std::vector< std::vector<unsigned> > line_segment_map(nLines);
 	for (std::size_t i=0; i<nLines; ++i)
 	{
diff --git a/MeshGeoToolsLib/MeshNodesAlongPolyline.cpp b/MeshGeoToolsLib/MeshNodesAlongPolyline.cpp
index 2795f044615e73faeb1619d8e71dfa53482bd31d..aab12d85138b6ebe5aa8424e3bf92c3dcbbd0796 100644
--- a/MeshGeoToolsLib/MeshNodesAlongPolyline.cpp
+++ b/MeshGeoToolsLib/MeshNodesAlongPolyline.cpp
@@ -33,7 +33,7 @@ MeshNodesAlongPolyline::MeshNodesAlongPolyline(
 	const std::size_t n_nodes (search_all_nodes ? _mesh.getNNodes() : _mesh.getNBaseNodes());
 	auto &mesh_nodes = _mesh.getNodes();
 	// loop over all nodes
-	for (size_t i = 0; i < n_nodes; i++) {
+	for (std::size_t i = 0; i < n_nodes; i++) {
 		double dist = _ply.getDistanceAlongPolyline(*mesh_nodes[i], epsilon_radius);
 		if (dist >= 0.0) {
 			_msh_node_ids.push_back(mesh_nodes[i]->getID());
@@ -51,7 +51,7 @@ MeshLib::Mesh const& MeshNodesAlongPolyline::getMesh () const
 	return _mesh;
 }
 
-std::vector<size_t> const& MeshNodesAlongPolyline::getNodeIDs () const
+std::vector<std::size_t> const& MeshNodesAlongPolyline::getNodeIDs () const
 {
 	return _msh_node_ids;
 }
diff --git a/MeshGeoToolsLib/MeshNodesAlongSurface.cpp b/MeshGeoToolsLib/MeshNodesAlongSurface.cpp
index 79b61cd03c7a2098fb317c1e76e04c6df8d9b59a..bf25042943627827e00acb23fec9e1b55023e0c1 100644
--- a/MeshGeoToolsLib/MeshNodesAlongSurface.cpp
+++ b/MeshGeoToolsLib/MeshNodesAlongSurface.cpp
@@ -30,7 +30,7 @@ MeshNodesAlongSurface::MeshNodesAlongSurface(
 	auto& mesh_nodes = _mesh.getNodes();
 	const std::size_t n_nodes (search_all_nodes ? _mesh.getNNodes() : _mesh.getNBaseNodes());
 	// loop over all nodes
-	for (size_t i = 0; i < n_nodes; i++) {
+	for (std::size_t i = 0; i < n_nodes; i++) {
 		auto* node = mesh_nodes[i];
 		if (!sfc.isPntInBoundingVolume(node->getCoords()))
 			continue;