diff --git a/xs/src/ExPolygon.cpp b/xs/src/ExPolygon.cpp
index 366b4de70..d2088d465 100644
--- a/xs/src/ExPolygon.cpp
+++ b/xs/src/ExPolygon.cpp
@@ -6,7 +6,8 @@ namespace Slic3r {
 
 ExPolygon::operator Polygons() const
 {
-    Polygons polygons(this->holes.size() + 1);
+    Polygons polygons;
+    polygons.reserve(this->holes.size() + 1);
     polygons.push_back(this->contour);
     for (Polygons::const_iterator it = this->holes.begin(); it != this->holes.end(); ++it) {
         polygons.push_back(*it);
@@ -64,7 +65,7 @@ ExPolygon::is_valid() const
 bool
 ExPolygon::contains_line(const Line* line) const
 {
-    Polylines pl(1);
+    Polylines pl;
     pl.push_back(*line);
     
     Polylines pl_out;
@@ -85,7 +86,8 @@ ExPolygon::contains_point(const Point* point) const
 Polygons
 ExPolygon::simplify_p(double tolerance) const
 {
-    Polygons pp(this->holes.size() + 1);
+    Polygons pp;
+    pp.reserve(this->holes.size() + 1);
     
     // contour
     Polygon p = this->contour;
diff --git a/xs/src/Polyline.cpp b/xs/src/Polyline.cpp
index dc05043ac..5f62b5b47 100644
--- a/xs/src/Polyline.cpp
+++ b/xs/src/Polyline.cpp
@@ -5,7 +5,7 @@ namespace Slic3r {
 
 Polyline::operator Polylines() const
 {
-    Polylines polylines(1);
+    Polylines polylines;
     polylines.push_back(*this);
     return polylines;
 }
diff --git a/xs/src/Surface.cpp b/xs/src/Surface.cpp
index 085756b86..e82cf8079 100644
--- a/xs/src/Surface.cpp
+++ b/xs/src/Surface.cpp
@@ -24,6 +24,15 @@ Surface::is_bridge() const
 }
 
 #ifdef SLIC3RXS
+void
+Surface::from_SV_check(SV* surface_sv)
+{
+    if (!sv_isa(surface_sv, "Slic3r::Surface") && !sv_isa(surface_sv, "Slic3r::Surface::Ref"))
+        CONFESS("Not a valid Slic3r::Surface object");
+    // a XS Surface was supplied
+    *this = *(Surface *)SvIV((SV*)SvRV( surface_sv ));
+}
+
 SV*
 Surface::to_SV_ref() {
     SV* sv = newSV(0);
diff --git a/xs/src/Surface.hpp b/xs/src/Surface.hpp
index 304cc4572..cf89b1ac6 100644
--- a/xs/src/Surface.hpp
+++ b/xs/src/Surface.hpp
@@ -21,6 +21,7 @@ class Surface
     bool is_bridge() const;
     
     #ifdef SLIC3RXS
+    void from_SV_check(SV* surface_sv);
     SV* to_SV_ref();
     SV* to_SV_clone_ref() const;
     #endif
diff --git a/xs/xsp/SurfaceCollection.xsp b/xs/xsp/SurfaceCollection.xsp
index 4219bbe65..6665a0a24 100644
--- a/xs/xsp/SurfaceCollection.xsp
+++ b/xs/xsp/SurfaceCollection.xsp
@@ -22,7 +22,7 @@ SurfaceCollection::new(...)
         RETVAL->surfaces.resize(items-1);
         for (unsigned int i = 1; i < items; i++) {
             // Note: a COPY of the input is stored
-            RETVAL->surfaces[i-1] = *(Surface *)SvIV((SV*)SvRV( ST(i) ));
+            RETVAL->surfaces[i-1].from_SV_check(ST(i));
         }
     OUTPUT:
         RETVAL
@@ -56,8 +56,9 @@ void
 SurfaceCollection::append(...)
     CODE:
         for (unsigned int i = 1; i < items; i++) {
-            // Note: a COPY of the input is stored
-            THIS->surfaces.push_back(*(Surface *)SvIV((SV*)SvRV( ST(i) )));
+            Surface surface;
+            surface.from_SV_check( ST(i) );
+            THIS->surfaces.push_back(surface);
         }
 
 void