diff --git a/lib/Slic3r/Layer.pm b/lib/Slic3r/Layer.pm
index ff59de281..83ffceb08 100644
--- a/lib/Slic3r/Layer.pm
+++ b/lib/Slic3r/Layer.pm
@@ -218,7 +218,7 @@ sub make_surfaces {
                 }
                 
                 $next_lines
-                    or die sprintf("No lines start at point %s. This shouldn't happen. Please check the model for manifoldness.", $get_point_id->($points[-1]));
+                    or die sprintf("No lines start at point %s. This shouldn't happen. Please check the model for manifoldness.\n", $get_point_id->($points[-1]));
                 last CYCLE if !@$next_lines;
                 
                 my @ordered_next_lines = sort 
@@ -300,7 +300,7 @@ sub make_surfaces {
         warn $@ if $@;
         
         if (@discarded_lines) {
-            print "  Warning: even slow detection algorithm throwed errors. Review the output before printing.\n";
+            print "  Warning: even slow detection algorithm threw errors. Review the output before printing.\n";
         }
     }
     
@@ -449,7 +449,8 @@ sub process_bridges {
         my $unique_type = sub { $_[0]->surface_type . "_" . ($_[0]->bridge_angle || '') };
         my @unique_types = ();
         foreach my $bridge (@{$self->bridges}) {
-            push @unique_types, $unique_type->($bridge);
+            my $type = $unique_type->($bridge);
+            push @unique_types, $type unless grep $_ eq $type, @unique_types;
         }
         
         # merge bridges of the same type, removing any of the bridges already merged;
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 791a042db..c5abab33c 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -218,7 +218,7 @@ sub discover_horizontal_shells {
                 Slic3r::debugf "  looking for neighbors on layer %d...\n", $n;
                 
                 foreach my $surfaces (@{$self->layers->[$n]->fill_surfaces}) {
-                    my $neighbor_polygons = [ map $_->p, grep $_->surface_type eq 'internal', @$surfaces ];
+                    my $neighbor_polygons = [ map $_->p, @$surfaces ];
                     
                     # find intersection between @surfaces and current layer's surfaces
                     # intersections have contours and holes
@@ -235,26 +235,14 @@ sub discover_horizontal_shells {
                     
                     # assign resulting inner surfaces to layer
                     @$surfaces = ();
-                    foreach my $p (@$internal_polygons) {
-                        push @$surfaces, Slic3r::Surface->new(
-                            surface_type => 'internal',
-                            contour => $p->contour->closed_polyline,
-                            holes   => [
-                                map $_->closed_polyline, $p->holes,
-                            ],
-                        );
-                    }
+                    push @$surfaces, Slic3r::Surface->cast_from_expolygon
+                        ($_, surface_type => 'internal')
+                        for @$internal_polygons;
                     
                     # assign new internal-solid surfaces to layer
-                    foreach my $p (@$intersections) {
-                        push @$surfaces, Slic3r::Surface->new(
-                            surface_type => 'internal-solid',
-                            contour => $p->contour->closed_polyline,
-                            holes   => [
-                                map $_->closed_polyline, $p->holes,
-                            ],
-                        );
-                    }
+                    push @$surfaces, Slic3r::Surface->cast_from_expolygon
+                        ($_, surface_type => 'internal-solid')
+                        for @$intersections;
                 }
             }
         }