diff -up openscad-openscad-2019.01-RC2/openscad.pro.polyclipping openscad-openscad-2019.01-RC2/openscad.pro

--- openscad-openscad-2019.01-RC2/openscad.pro.polyclipping	2019-02-15 14:14:00.356626672 -0500

+++ openscad-openscad-2019.01-RC2/openscad.pro	2019-02-15 14:14:19.488249681 -0500

@@ -559,8 +559,7 @@ SOURCES += src/ext/lodepng/lodepng.cpp

 HEADERS += src/ext/lodepng/lodepng.h

 # ClipperLib

-SOURCES += src/ext/polyclipping/clipper.cpp

-HEADERS += src/ext/polyclipping/clipper.hpp

+LIBS += -lpolyclipping

 # libtess2

 INCLUDEPATH += src/ext/libtess2/Include

diff -up openscad-openscad-2019.01-RC2/src/clipper-utils.h.polyclipping openscad-openscad-2019.01-RC2/src/clipper-utils.h

--- openscad-openscad-2019.01-RC2/src/clipper-utils.h.polyclipping	2019-02-15 14:14:31.068021503 -0500

+++ openscad-openscad-2019.01-RC2/src/clipper-utils.h	2019-02-15 14:14:49.640655527 -0500

@@ -1,6 +1,6 @@

 #pragma once

-#include "ext/polyclipping/clipper.hpp"

+#include <polyclipping/clipper.hpp>

 #include "Polygon2d.h"

 namespace ClipperUtils {

diff -up openscad-openscad-2019.01-RC2/src/libsvg/shape.h.polyclipping openscad-openscad-2019.01-RC2/src/libsvg/shape.h

--- openscad-openscad-2019.01-RC2/src/libsvg/shape.h.polyclipping	2019-02-15 15:03:16.651372730 -0500

+++ openscad-openscad-2019.01-RC2/src/libsvg/shape.h	2019-02-15 15:03:26.240183783 -0500

@@ -34,7 +34,7 @@

 #include <Eigen/Geometry>

 #include "util.h"

-#include "ext/polyclipping/clipper.hpp"

+#include <polyclipping/clipper.hpp>

 namespace libsvg {