diff --git a/src/libslic3r/Geometry/VoronoiOffset.cpp b/src/libslic3r/Geometry/VoronoiOffset.cpp
index 46105220a..ed8d9c2b1 100644
--- a/src/libslic3r/Geometry/VoronoiOffset.cpp
+++ b/src/libslic3r/Geometry/VoronoiOffset.cpp
@@ -782,6 +782,9 @@ void annotate_inside_outside(VD &vd, const Lines &lines)
 
     for (const VD::edge_type &edge : vd.edges())
         if (edge.vertex1() == nullptr) {
+            if (edge.vertex0() == nullptr)
+                continue;
+
             // Infinite Voronoi edge separating two Point sites or a Point site and a Segment site.
             // Infinite edge is always outside and it references at least one valid vertex.
             assert(edge.is_infinite());
@@ -888,6 +891,9 @@ void annotate_inside_outside(VD &vd, const Lines &lines)
     for (const VD::edge_type &edge : vd.edges()) {
         assert((edge_category(edge) == EdgeCategory::Unknown) == (edge_category(edge.twin()) == EdgeCategory::Unknown));
         if (edge_category(edge) == EdgeCategory::Unknown) {
+            if (!edge.is_finite())
+                continue;
+
             assert(edge.is_finite());
             const VD::cell_type &cell   = *edge.cell();
             const VD::cell_type &cell2  = *edge.twin()->cell();