diff --git a/lib/Slic3r/Fill/Honeycomb.pm b/lib/Slic3r/Fill/Honeycomb.pm
index e5c515bcc..6e665a70b 100644
--- a/lib/Slic3r/Fill/Honeycomb.pm
+++ b/lib/Slic3r/Fill/Honeycomb.pm
@@ -118,7 +118,7 @@ sub fill_surface {
         # clip paths again to prevent connection segments from crossing the expolygon boundaries
         @paths = @{intersection_pl(
             \@paths,
-            [ @{$surface->expolygon->offset_ex(scaled_epsilon)} ],
+            [ map @$_, @{$surface->expolygon->offset_ex(scaled_epsilon)} ],
         )};
     }
     
diff --git a/lib/Slic3r/Layer/Region.pm b/lib/Slic3r/Layer/Region.pm
index 717207275..d8c607d65 100644
--- a/lib/Slic3r/Layer/Region.pm
+++ b/lib/Slic3r/Layer/Region.pm
@@ -132,7 +132,7 @@ sub make_perimeters {
         
         # make sure we don't infill narrow parts that are already gap-filled
         # (we only consider this surface's gaps to reduce the diff() complexity)
-        @last = @{diff(\@last, \@last_gaps)};
+        @last = @{diff(\@last, [ map @$_, @last_gaps ])};
         
         # create one more offset to be used as boundary for fill
         # we offset by half the perimeter spacing (to get to the actual infill boundary)
@@ -420,7 +420,7 @@ sub _detect_bridge_direction {
     my $perimeter_flow  = $self->flow(FLOW_ROLE_PERIMETER);
     my $infill_flow     = $self->flow(FLOW_ROLE_INFILL);
     
-    my $grown = $expolygon->offset_ex(+$perimeter_flow->scaled_width);
+    my $grown = $expolygon->offset(+$perimeter_flow->scaled_width);
     my @lower = @{$lower_layer->slices};       # expolygons
     
     # detect what edges lie on lower slices
@@ -428,7 +428,7 @@ sub _detect_bridge_direction {
     foreach my $lower (@lower) {
         # turn bridge contour and holes into polylines and then clip them
         # with each lower slice's contour
-        my @clipped = @{intersection_pl([ map $_->split_at_first_point, map @$_, @$grown ], [$lower->contour])};
+        my @clipped = @{intersection_pl([ map $_->split_at_first_point, @$grown ], [$lower->contour])};
         if (@clipped == 2) {
             # If the split_at_first_point() call above happens to split the polygon inside the clipping area
             # we would get two consecutive polylines instead of a single one, so we use this ugly hack to 
@@ -479,7 +479,7 @@ sub _detect_bridge_direction {
         
         # detect anchors as intersection between our bridge expolygon and the lower slices
         my $anchors = intersection_ex(
-            [ @$grown ],
+            $grown,
             [ map @$_, @lower ],
             1,  # safety offset required to avoid Clipper from detecting empty intersection while Boost actually found some @edges
         );
diff --git a/xs/src/ExPolygon.cpp b/xs/src/ExPolygon.cpp
index a3cb4f7fd..366b4de70 100644
--- a/xs/src/ExPolygon.cpp
+++ b/xs/src/ExPolygon.cpp
@@ -180,6 +180,8 @@ void
 ExPolygon::from_SV_check(SV* expoly_sv)
 {
     if (sv_isobject(expoly_sv) && (SvTYPE(SvRV(expoly_sv)) == SVt_PVMG)) {
+        if (!sv_isa(expoly_sv, "Slic3r::ExPolygon") && !sv_isa(expoly_sv, "Slic3r::ExPolygon::Ref"))
+            CONFESS("Not a valid Slic3r::ExPolygon object");
         // a XS ExPolygon was supplied
         *this = *(ExPolygon *)SvIV((SV*)SvRV( expoly_sv ));
     } else {
diff --git a/xs/src/Line.cpp b/xs/src/Line.cpp
index 66f3d860f..7c0a16032 100644
--- a/xs/src/Line.cpp
+++ b/xs/src/Line.cpp
@@ -88,6 +88,8 @@ void
 Line::from_SV_check(SV* line_sv)
 {
     if (sv_isobject(line_sv) && (SvTYPE(SvRV(line_sv)) == SVt_PVMG)) {
+        if (!sv_isa(line_sv, "Slic3r::Line") && !sv_isa(line_sv, "Slic3r::Line::Ref"))
+            CONFESS("Not a valid Slic3r::Line object");
         *this = *(Line*)SvIV((SV*)SvRV( line_sv ));
     } else {
         this->from_SV(line_sv);
diff --git a/xs/src/Point.cpp b/xs/src/Point.cpp
index b6742a9d2..7d9d7e12d 100644
--- a/xs/src/Point.cpp
+++ b/xs/src/Point.cpp
@@ -169,6 +169,8 @@ void
 Point::from_SV_check(SV* point_sv)
 {
     if (sv_isobject(point_sv) && (SvTYPE(SvRV(point_sv)) == SVt_PVMG)) {
+        if (!sv_isa(point_sv, "Slic3r::Point") && !sv_isa(point_sv, "Slic3r::Point::Ref"))
+            CONFESS("Not a valid Slic3r::Point object");
         *this = *(Point*)SvIV((SV*)SvRV( point_sv ));
     } else {
         this->from_SV(point_sv);
diff --git a/xs/src/Polygon.cpp b/xs/src/Polygon.cpp
index 0fae5799d..4d6e01e6b 100644
--- a/xs/src/Polygon.cpp
+++ b/xs/src/Polygon.cpp
@@ -166,6 +166,15 @@ Polygon::to_SV_clone_ref() const {
     sv_setref_pv( sv, "Slic3r::Polygon", new Polygon(*this) );
     return sv;
 }
+
+void
+Polygon::from_SV_check(SV* poly_sv)
+{
+    if (sv_isobject(poly_sv) && !sv_isa(poly_sv, "Slic3r::Polygon") && !sv_isa(poly_sv, "Slic3r::Polygon::Ref"))
+        CONFESS("Not a valid Slic3r::Polygon object");
+    
+    MultiPoint::from_SV_check(poly_sv);
+}
 #endif
 
 }
diff --git a/xs/src/Polygon.hpp b/xs/src/Polygon.hpp
index e4e9dab92..b4c21993b 100644
--- a/xs/src/Polygon.hpp
+++ b/xs/src/Polygon.hpp
@@ -32,6 +32,7 @@ class Polygon : public MultiPoint {
     void simplify(double tolerance, Polygons &polygons) const;
     
     #ifdef SLIC3RXS
+    void from_SV_check(SV* poly_sv);
     SV* to_SV_ref();
     SV* to_SV_clone_ref() const;
     #endif
diff --git a/xs/src/Polyline.cpp b/xs/src/Polyline.cpp
index c2801d74c..dc05043ac 100644
--- a/xs/src/Polyline.cpp
+++ b/xs/src/Polyline.cpp
@@ -110,6 +110,15 @@ Polyline::to_SV_clone_ref() const
     sv_setref_pv( sv, "Slic3r::Polyline", new Polyline(*this) );
     return sv;
 }
+
+void
+Polyline::from_SV_check(SV* poly_sv)
+{
+    if (!sv_isa(poly_sv, "Slic3r::Polyline") && !sv_isa(poly_sv, "Slic3r::Polyline::Ref"))
+        CONFESS("Not a valid Slic3r::Polyline object");
+    
+    MultiPoint::from_SV_check(poly_sv);
+}
 #endif
 
 }
diff --git a/xs/src/Polyline.hpp b/xs/src/Polyline.hpp
index 3b9b95694..394edf4f2 100644
--- a/xs/src/Polyline.hpp
+++ b/xs/src/Polyline.hpp
@@ -20,6 +20,7 @@ class Polyline : public MultiPoint {
     void simplify(double tolerance);
     
     #ifdef SLIC3RXS
+    void from_SV_check(SV* poly_sv);
     SV* to_SV_ref();
     SV* to_SV_clone_ref() const;
     #endif