diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 2cf12bf63..a0ac953ba 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -151,7 +151,9 @@ sub validate {
                 {
                     my @points = map [ @$_[X,Y] ], map @{$_->vertices}, @{$self->objects->[$obj_idx]->meshes};
                     my $convex_hull = Slic3r::Polygon->new(convex_hull(\@points));
-                    ($clearance) = offset([$convex_hull], scale $Slic3r::Config->extruder_clearance_radius / 2, 1, JT_ROUND);
+                    ($clearance) = map Slic3r::Polygon->new($_), 
+                                        Slic3r::Geometry::Clipper::offset(
+                                            [$convex_hull], scale $Slic3r::Config->extruder_clearance_radius / 2, 1, JT_ROUND);
                 }
                 for my $copy (@{$self->objects->[$obj_idx]->copies}) {
                     my $copy_clearance = $clearance->clone;