diff --git a/src/libslic3r/IntersectionPoints.cpp b/src/libslic3r/IntersectionPoints.cpp
index 3537e74ab..78d192397 100644
--- a/src/libslic3r/IntersectionPoints.cpp
+++ b/src/libslic3r/IntersectionPoints.cpp
@@ -106,6 +106,7 @@ Slic3r::Pointfs Slic3r::intersection_points(const ExPolygons &expolygons)
 #include <libslic3r/BoundingBox.hpp>
 
 namespace priv {
+//FIXME O(n^2) complexity!
 Slic3r::Pointfs compute_intersections(const Slic3r::Lines &lines)
 {
     using namespace Slic3r;
diff --git a/src/libslic3r/IntersectionPoints.hpp b/src/libslic3r/IntersectionPoints.hpp
index 2b1d3aa73..7603765d9 100644
--- a/src/libslic3r/IntersectionPoints.hpp
+++ b/src/libslic3r/IntersectionPoints.hpp
@@ -6,6 +6,7 @@
 namespace Slic3r {
 
 // collect all intersecting points
+//FIXME O(n^2) complexity!
 Pointfs intersection_points(const Lines &lines);
 Pointfs intersection_points(const Polygon &polygon);
 Pointfs intersection_points(const Polygons &polygons);