diff --git a/shard.yml b/shard.yml
index 9c2242b..bb03796 100644
--- a/shard.yml
+++ b/shard.yml
@@ -16,6 +16,7 @@ dependencies:
     github: geocrystal/geo_bearing
   ring_area:
     github: geocrystal/ring_area
+    version: ">= 0.2.1"
   geojson:
     github: geocrystal/geojson
 
diff --git a/spec/geo/polygon_spec.cr b/spec/geo/polygon_spec.cr
index 94c88d0..afaf15b 100644
--- a/spec/geo/polygon_spec.cr
+++ b/spec/geo/polygon_spec.cr
@@ -97,7 +97,8 @@ describe Geo::Polygon do
 
     polygon = Geo::Polygon.new(coords)
 
-    it { polygon.area.should eq(7748891609977.457) }
+    it { polygon.area.should be_a(RingArea::Area) }
+    it { polygon.area.to_meters.should eq(7748891609977.457) }
   end
 
   describe "#to_geojson" do