diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 87d83b297..eb81df845 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -783,7 +783,7 @@ sub write_gcode {
         
         # print objects from the smallest to the tallest to avoid collisions
         # when moving onto next object starting point
-        my @obj_idx = sort { $self->objects->[$a]->layer_count <=> $self->objects->[$b]->layer_count } 0..$#{$self->objects};
+        my @obj_idx = sort { $self->objects->[$a]->size->[Z] <=> $self->objects->[$b]->size->[Z] } 0..$#{$self->objects};
         
         my $finished_objects = 0;
         for my $obj_idx (@obj_idx) {
diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index dc5428dc9..bfc46ce62 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -11,7 +11,7 @@ use Slic3r::Surface ':types';
 has 'print'             => (is => 'ro', weak_ref => 1, required => 1);
 has 'input_file'        => (is => 'rw', required => 0);
 has 'meshes'            => (is => 'rw', default => sub { [] });  # by region_id
-has 'size'              => (is => 'rw', required => 1);
+has 'size'              => (is => 'rw', required => 1); # XYZ in scaled coordinates
 has 'copies'            => (is => 'rw', trigger => 1);  # in scaled coordinates
 has 'layers'            => (is => 'rw', default => sub { [] });
 has 'layer_height_ranges' => (is => 'rw', default => sub { [] }); # [ z_min, z_max, layer_height ]