diff --git a/lib/geo_ruby/gpx.rb b/lib/geo_ruby/gpx.rb
index 10a1a26..71649b1 100644
--- a/lib/geo_ruby/gpx.rb
+++ b/lib/geo_ruby/gpx.rb
@@ -73,7 +73,7 @@ def as_line_string
       # If the GPX isn't closed, a line from the first
       # to the last point will be created to close it.
       def as_polygon
-        GeoRuby::SimpleFeatures::Polygon.from_points([@points[0] == @points[-1] ?  @points : @points.push(@points[0].clone)])
+        GeoRuby::SimpleFeatures::Polygon.from_points([@points[0] == @points[-1] ?  @points : (@points + [@points[0]])])
       end
 
       # Return GPX Envelope