diff --git a/src/libslic3r/SLA/SupportTreeUtils.hpp b/src/libslic3r/SLA/SupportTreeUtils.hpp
index 9c3c1f5849..d5707dc5c1 100644
--- a/src/libslic3r/SLA/SupportTreeUtils.hpp
+++ b/src/libslic3r/SLA/SupportTreeUtils.hpp
@@ -498,7 +498,8 @@ std::vector<size_t> non_duplicate_suppt_indices(const PtIndex &index,
                                           !to_remove[i_closest];
                                });
 
-        if ((suppts[i].pos - suppts[closest_idx].pos).norm() < eps)
+        if (closest_idx < suppts.size() &&
+            (suppts[i].pos - suppts[closest_idx].pos).norm() < eps)
             to_remove[i] = true;
     }