diff --git a/lib/Slic3r/ExtrusionPath.pm b/lib/Slic3r/ExtrusionPath.pm
index be97e3baa..5b8cff611 100644
--- a/lib/Slic3r/ExtrusionPath.pm
+++ b/lib/Slic3r/ExtrusionPath.pm
@@ -27,22 +27,6 @@ sub clip_with_expolygon {
         $self->polyline->clip_with_expolygon($expolygon);
 }
 
-sub intersect_expolygons {
-    my $self = shift;
-    my ($expolygons_pp) = @_;
-    
-    return map $self->clone(polyline => Slic3r::Polyline->new(@$_)),
-        @{Boost::Geometry::Utils::multi_polygon_multi_linestring_intersection($expolygons_pp, [$self->pp])};
-}
-
-sub subtract_expolygons {
-    my $self = shift;
-    my ($expolygons_pp) = @_;
-    
-    return map $self->clone(polyline => Slic3r::Polyline->new(@$_)),
-        @{Boost::Geometry::Utils::multi_linestring_multi_polygon_difference([$self->pp], $expolygons_pp)};
-}
-
 sub simplify {
     my $self = shift;
     $self->polyline($self->polyline->simplify(@_));
diff --git a/lib/Slic3r/GCode.pm b/lib/Slic3r/GCode.pm
index 55ae1b6e4..008ab4669 100644
--- a/lib/Slic3r/GCode.pm
+++ b/lib/Slic3r/GCode.pm
@@ -17,7 +17,7 @@ has 'layer_count'        => (is => 'ro', required => 1 );
 has 'layer'              => (is => 'rw');
 has '_layer_islands'     => (is => 'rw');
 has '_upper_layer_islands'  => (is => 'rw');
-has '_layer_overhangs_pp' => (is => 'rw');
+has '_layer_overhangs'   => (is => 'ro', default => sub { Slic3r::ExPolygon::Collection->new });
 has 'shift_x'            => (is => 'rw', default => sub {0} );
 has 'shift_y'            => (is => 'rw', default => sub {0} );
 has 'z'                  => (is => 'rw');
@@ -95,12 +95,13 @@ sub change_layer {
     # avoid computing islands and overhangs if they're not needed
     $self->_layer_islands($layer->islands);
     $self->_upper_layer_islands($layer->upper_layer ? $layer->upper_layer->islands : []);
-    $self->_layer_overhangs_pp(
-        # clone ExPolygons because they come from Surface objects but will be used outside here
-        ($layer->id > 0 && ($layer->config->overhangs || $Slic3r::Config->start_perimeters_at_non_overhang))
-            ? [ map $_->expolygon->pp, grep $_->surface_type == S_TYPE_BOTTOM, map @{$_->slices}, @{$layer->regions} ]
-            : []
+    $self->_layer_overhangs->clear;
+    if ($layer->id > 0 && ($layer->config->overhangs || $Slic3r::Config->start_perimeters_at_non_overhang)) {
+        $self->_layer_overhangs->append(
+            # clone ExPolygons because they come from Surface objects but will be used outside here
+            map $_->expolygon, map @{$_->slices->filter_by_type(S_TYPE_BOTTOM)}, @{$layer->regions}
         );
+    }
     if ($self->config->avoid_crossing_perimeters) {
         $self->layer_mp(Slic3r::GCode::MotionPlanner->new(
             islands => union_ex([ map @$_, @{$layer->slices} ], 1),
@@ -176,7 +177,7 @@ sub extrude_loop {
     }
     my @candidates = ();
     if ($Slic3r::Config->start_perimeters_at_non_overhang) {
-        @candidates = grep !Boost::Geometry::Utils::point_covered_by_multi_polygon($_->pp, $self->_layer_overhangs_pp), @concave;
+        @candidates = grep !$self->_layer_overhangs->contains_point($_), @concave;
     }
     if (!@candidates) {
         # if none, look for any concave vertex
@@ -184,7 +185,7 @@ sub extrude_loop {
         if (!@candidates) {
             # if none, look for any non-overhang vertex
             if ($Slic3r::Config->start_perimeters_at_non_overhang) {
-                @candidates = grep !Boost::Geometry::Utils::point_covered_by_multi_polygon($_->pp, $self->_layer_overhangs_pp), @$polygon;
+                @candidates = grep !$self->_layer_overhangs->contains_point($_), @$polygon;
             }
             if (!@candidates) {
                 # if none, all points are valid candidates
@@ -214,10 +215,11 @@ sub extrude_loop {
     
     my @paths = ();
     # detect overhanging/bridging perimeters
-    if ($self->layer->config->overhangs && $extrusion_path->is_perimeter && @{$self->_layer_overhangs_pp}) {
+    if ($self->layer->config->overhangs && $extrusion_path->is_perimeter && $self->_layer_overhangs->count > 0) {
         # get non-overhang paths by subtracting overhangs from the loop
         push @paths,
-            $extrusion_path->subtract_expolygons($self->_layer_overhangs_pp);
+            map $_->clone,
+            @{$extrusion_path->subtract_expolygons($self->_layer_overhangs)};
         
         # get overhang paths by intersecting overhangs with the loop
         push @paths,
@@ -226,7 +228,8 @@ sub extrude_loop {
                 $_->flow_spacing($self->extruder->bridge_flow->width);
                 $_
             }
-            $extrusion_path->intersect_expolygons($self->_layer_overhangs_pp);
+            map $_->clone,
+            @{$extrusion_path->intersect_expolygons($self->_layer_overhangs)};
         
         # reapply the nearest point search for starting point
         # (clone because the collection gets DESTROY'ed)
diff --git a/xs/src/ExPolygonCollection.cpp b/xs/src/ExPolygonCollection.cpp
index d0f84990c..da257ca39 100644
--- a/xs/src/ExPolygonCollection.cpp
+++ b/xs/src/ExPolygonCollection.cpp
@@ -2,6 +2,18 @@
 
 namespace Slic3r {
 
+ExPolygonCollection::operator Polygons() const
+{
+    Polygons polygons;
+    for (ExPolygons::const_iterator it = this->expolygons.begin(); it != this->expolygons.end(); ++it) {
+        polygons.push_back(it->contour);
+        for (Polygons::const_iterator ith = it->holes.begin(); ith != it->holes.end(); ++ith) {
+            polygons.push_back(*ith);
+        }
+    }
+    return polygons;
+}
+
 void
 ExPolygonCollection::scale(double factor)
 {
@@ -26,4 +38,13 @@ ExPolygonCollection::rotate(double angle, Point* center)
     }
 }
 
+bool
+ExPolygonCollection::contains_point(const Point* point) const
+{
+    for (ExPolygons::const_iterator it = this->expolygons.begin(); it != this->expolygons.end(); ++it) {
+        if (it->contains_point(point)) return true;
+    }
+    return false;
+}
+
 }
diff --git a/xs/src/ExPolygonCollection.hpp b/xs/src/ExPolygonCollection.hpp
index 357b7fb50..d4b7d8162 100644
--- a/xs/src/ExPolygonCollection.hpp
+++ b/xs/src/ExPolygonCollection.hpp
@@ -10,9 +10,11 @@ class ExPolygonCollection
 {
     public:
     ExPolygons expolygons;
+    operator Polygons() const;
     void scale(double factor);
     void translate(double x, double y);
     void rotate(double angle, Point* center);
+    bool contains_point(const Point* point) const;
 };
 
 }
diff --git a/xs/src/ExtrusionEntity.cpp b/xs/src/ExtrusionEntity.cpp
index 974e8910f..e6461a9f8 100644
--- a/xs/src/ExtrusionEntity.cpp
+++ b/xs/src/ExtrusionEntity.cpp
@@ -1,4 +1,7 @@
 #include "ExtrusionEntity.hpp"
+#include "ExtrusionEntityCollection.hpp"
+#include "ExPolygonCollection.hpp"
+#include "ClipperUtils.hpp"
 
 namespace Slic3r {
 
@@ -26,6 +29,36 @@ ExtrusionPath::last_point() const
     return new Point(this->polyline.points.back());
 }
 
+ExtrusionEntityCollection*
+ExtrusionPath::intersect_expolygons(ExPolygonCollection* collection) const
+{
+    // perform clipping
+    Polylines clipped;
+    intersection(this->polyline, *collection, clipped);
+    return this->_inflate_collection(clipped);
+}
+
+ExtrusionEntityCollection*
+ExtrusionPath::subtract_expolygons(ExPolygonCollection* collection) const
+{
+    // perform clipping
+    Polylines clipped;
+    diff(this->polyline, *collection, clipped);
+    return this->_inflate_collection(clipped);
+}
+
+ExtrusionEntityCollection*
+ExtrusionPath::_inflate_collection(const Polylines &polylines) const
+{
+    ExtrusionEntityCollection* retval = new ExtrusionEntityCollection();
+    for (Polylines::const_iterator it = polylines.begin(); it != polylines.end(); ++it) {
+        ExtrusionPath* path = this->clone();
+        path->polyline = *it;
+        retval->entities.push_back(path);
+    }
+    return retval;
+}
+
 ExtrusionLoop*
 ExtrusionLoop::clone() const
 {
diff --git a/xs/src/ExtrusionEntity.hpp b/xs/src/ExtrusionEntity.hpp
index c9dd6b080..6d5dc9a89 100644
--- a/xs/src/ExtrusionEntity.hpp
+++ b/xs/src/ExtrusionEntity.hpp
@@ -7,6 +7,9 @@
 
 namespace Slic3r {
 
+class ExPolygonCollection;
+class ExtrusionEntityCollection;
+
 enum ExtrusionRole {
     erPerimeter,
     erExternalPerimeter,
@@ -45,6 +48,10 @@ class ExtrusionPath : public ExtrusionEntity
     void reverse();
     Point* first_point() const;
     Point* last_point() const;
+    ExtrusionEntityCollection* intersect_expolygons(ExPolygonCollection* collection) const;
+    ExtrusionEntityCollection* subtract_expolygons(ExPolygonCollection* collection) const;
+    private:
+    ExtrusionEntityCollection* _inflate_collection(const Polylines &polylines) const;
 };
 
 class ExtrusionLoop : public ExtrusionEntity
diff --git a/xs/src/Polyline.cpp b/xs/src/Polyline.cpp
index fc3950757..326a309d7 100644
--- a/xs/src/Polyline.cpp
+++ b/xs/src/Polyline.cpp
@@ -1,7 +1,15 @@
 #include "Polyline.hpp"
+#include "Polygon.hpp"
 
 namespace Slic3r {
 
+Polyline::operator Polylines() const
+{
+    Polylines polylines(1);
+    polylines.push_back(*this);
+    return polylines;
+}
+
 Point*
 Polyline::last_point() const
 {
diff --git a/xs/src/Polyline.hpp b/xs/src/Polyline.hpp
index c17b97f9f..59410dd2d 100644
--- a/xs/src/Polyline.hpp
+++ b/xs/src/Polyline.hpp
@@ -6,8 +6,12 @@
 
 namespace Slic3r {
 
+class Polyline;
+typedef std::vector<Polyline> Polylines;
+
 class Polyline : public MultiPoint {
     public:
+    operator Polylines() const;
     Point* last_point() const;
     Lines lines() const;
     void clip_end(double distance);
@@ -20,8 +24,6 @@ class Polyline : public MultiPoint {
     #endif
 };
 
-typedef std::vector<Polyline> Polylines;
-
 }
 
 #endif
diff --git a/xs/xsp/ExPolygonCollection.xsp b/xs/xsp/ExPolygonCollection.xsp
index 0e6e50c00..7a108235f 100644
--- a/xs/xsp/ExPolygonCollection.xsp
+++ b/xs/xsp/ExPolygonCollection.xsp
@@ -16,6 +16,7 @@
     void rotate(double angle, Point* center);
     int count()
         %code{% RETVAL = THIS->expolygons.size(); %};
+    bool contains_point(Point* point);
 %{
 
 ExPolygonCollection*
diff --git a/xs/xsp/ExtrusionPath.xsp b/xs/xsp/ExtrusionPath.xsp
index db2db16ad..2f92b3f45 100644
--- a/xs/xsp/ExtrusionPath.xsp
+++ b/xs/xsp/ExtrusionPath.xsp
@@ -20,6 +20,10 @@
         %code{% const char* CLASS = "Slic3r::Point"; RETVAL = THIS->first_point(); %};
     Point* last_point()
         %code{% const char* CLASS = "Slic3r::Point"; RETVAL = THIS->last_point(); %};
+    ExtrusionEntityCollection* intersect_expolygons(ExPolygonCollection* collection)
+        %code{% const char* CLASS = "Slic3r::ExtrusionPath::Collection"; RETVAL = THIS->intersect_expolygons(collection); %};
+    ExtrusionEntityCollection* subtract_expolygons(ExPolygonCollection* collection)
+        %code{% const char* CLASS = "Slic3r::ExtrusionPath::Collection"; RETVAL = THIS->subtract_expolygons(collection); %};
 %{
 
 ExtrusionPath*
diff --git a/xs/xsp/typemap.xspt b/xs/xsp/typemap.xspt
index 1928e91f2..22659855a 100644
--- a/xs/xsp/typemap.xspt
+++ b/xs/xsp/typemap.xspt
@@ -7,6 +7,7 @@
 %typemap{AV*};
 %typemap{Point*};
 %typemap{ExPolygon*};
+%typemap{ExPolygonCollection*};
 %typemap{Line*};
 %typemap{Polyline*};
 %typemap{Polygon*};