diff --git a/xs/src/libslic3r/BoundingBox.cpp b/xs/src/libslic3r/BoundingBox.cpp
index 2b3f00df18..bffe1dbfb1 100644
--- a/xs/src/libslic3r/BoundingBox.cpp
+++ b/xs/src/libslic3r/BoundingBox.cpp
@@ -271,7 +271,8 @@ template bool BoundingBoxBase<Pointf>::contains(const Pointf &point) const;
 template <class PointClass> bool
 BoundingBoxBase<PointClass>::overlap(const BoundingBoxBase<PointClass> &other) const
 {
-    return this->contains(other.min) || other.contains(this->min);
+    return ! (this->max.x < other.min.x || this->min.x > other.max.x ||
+              this->max.y < other.min.y || this->min.y > other.max.y);
 }
 template bool BoundingBoxBase<Point>::overlap(const BoundingBoxBase<Point> &point) const;
 template bool BoundingBoxBase<Pointf>::overlap(const BoundingBoxBase<Pointf> &point) const;
diff --git a/xs/src/libslic3r/ExPolygon.cpp b/xs/src/libslic3r/ExPolygon.cpp
index 76a48b46a5..4861a08fde 100644
--- a/xs/src/libslic3r/ExPolygon.cpp
+++ b/xs/src/libslic3r/ExPolygon.cpp
@@ -165,8 +165,22 @@ ExPolygon::has_boundary_point(const Point &point) const
 bool
 ExPolygon::overlaps(const ExPolygon &other) const
 {
+    #if 0
+    BoundingBox bbox = get_extents(other);
+    bbox.merge(get_extents(*this));
+    static int iRun = 0;
+    char path[2048];
+    sprintf(path, "out\\ExPolygon_overlaps-%d.svg", iRun ++);
+    SVG svg(path, bbox);
+    svg.draw(*this);
+    svg.draw_outline(*this);
+    svg.draw_outline(other, "blue");
+    #endif
     Polylines pl_out;
     intersection((Polylines)other, *this, &pl_out);
+    #if 0
+    svg.draw(pl_out, "red");
+    #endif
     if (! pl_out.empty())
         return true; 
     return ! other.contour.points.empty() && this->contains_b(other.contour.points.front());
diff --git a/xs/src/libslic3r/ExPolygon.hpp b/xs/src/libslic3r/ExPolygon.hpp
index f283822da3..ef3c153dcb 100644
--- a/xs/src/libslic3r/ExPolygon.hpp
+++ b/xs/src/libslic3r/ExPolygon.hpp
@@ -38,7 +38,7 @@ class ExPolygon
     // Does this expolygon overlap another expolygon?
     // Either the ExPolygons intersect, or one is fully inside the other,
     // and it is not inside a hole of the other expolygon.
-    bool overlap(const ExPolygon &other) const;
+    bool overlaps(const ExPolygon &other) const;
 
     void simplify_p(double tolerance, Polygons* polygons) const;
     Polygons simplify_p(double tolerance) const;