diff --git a/include/andres/graph/lifting.hxx b/include/andres/graph/lifting.hxx
index be057b7..2919c52 100755
--- a/include/andres/graph/lifting.hxx
+++ b/include/andres/graph/lifting.hxx
@@ -4,7 +4,8 @@
 
 #include <cassert>
 #include <cstddef>
-#include <cmath>
+#include <cstdlib> // std::abs
+#include <cmath> // std::abs since c++17
 #include <stdexcept>
 #include <iterator> // std::iterator_traits
 #include <algorithm> // std::fill
@@ -118,7 +119,7 @@ lift(
             {
                 const std::size_t offsetX = (metric == LiftingMetric::PathLength) ?
                                             distanceUpperBound - offsetY:
-                                            ::floor(::sqrt(distanceUpperBoundSquared - offsetY * offsetY));
+                                            std::floor(std::sqrt(distanceUpperBoundSquared - offsetY * offsetY));
 
                 const std::size_t col0 = cv[0] < offsetX ? 0 : cv[0] - offsetX;
                 std::size_t colN = cv[0] + offsetX;
@@ -129,7 +130,8 @@ lift(
                 {
                     if (metric == LiftingMetric::PathLength)
                     {
-                        const std::size_t distance = std::abs(x - cv[0]) + std::abs(yPlus - 1 - cv[1]);
+                        const std::size_t distance = std::abs(static_cast<long>(x - cv[0]))
+                            + std::abs(static_cast<long>(yPlus - 1 - cv[1]));
 
                         if (distance > distanceLowerBound)
                         {
@@ -189,7 +191,7 @@ lift(
             {
                 const std::size_t offsetX = (metric == LiftingMetric::PathLength) ?
                                             distanceUpperBound - offsetY :
-                                            ::floor(::sqrt(distanceUpperBoundSquared - offsetY * offsetY));
+                                            std::floor(std::sqrt(distanceUpperBoundSquared - offsetY * offsetY));
 
                 const std::size_t col0 = cv[0] < offsetX ? 0 : cv[0] - offsetX;
                 std::size_t colN = cv[0] + offsetX;
diff --git a/src/andres/graph/unit-test/lifting.cxx b/src/andres/graph/unit-test/lifting.cxx
index 435e77f..a01a5d4 100755
--- a/src/andres/graph/unit-test/lifting.cxx
+++ b/src/andres/graph/unit-test/lifting.cxx
@@ -64,6 +64,28 @@ void testLiftGridGraphPathLengthMetric() {
             andres::graph::Graph<> graphLifted;
             andres::graph::lift(graph, graphLifted, distanceUpperBound, distanceLowerBound); // tested by function testLiftGraph
 
+            /*
+            std::cout << "lb=" << distanceLowerBound
+                << ", up=" << distanceUpperBound
+                << std::endl;
+            for(size_t v = 0; v < gridGraph.numberOfVertices(); ++v) {
+                andres::graph::GridGraph<2>::VertexCoordinate vc;
+                gridGraph.vertex(v, vc);
+                std::cout << "neighbors of node "
+                    << "(" << vc[0] << ", " << vc[1] << ")" << std::endl;
+                for(auto it = graphLifted.verticesFromVertexBegin(v); it != graphLifted.verticesFromVertexEnd(v); ++it) {
+                    gridGraph.vertex(*it, vc);
+                    std::cout << "(" << vc[0] << ", " << vc[1] << ") ";
+                }
+                std::cout << std::endl;
+                for(auto it = gridGraphLifted.verticesFromVertexBegin(v); it != gridGraphLifted.verticesFromVertexEnd(v); ++it) {
+                    gridGraph.vertex(*it, vc);
+                    std::cout << "(" << vc[0] << ", " << vc[1] << ") ";
+                }
+                std::cout << std::endl;
+            }
+            */
+
             test(gridGraphLifted.numberOfVertices() == gridGraph.numberOfVertices());
             test(gridGraphLifted.numberOfEdges() == graphLifted.numberOfEdges());
             for(size_type v = 0; v < graphLifted.numberOfVertices(); ++v)