diff --git a/shard.yml b/shard.yml
index 047e6b4..42d778c 100644
--- a/shard.yml
+++ b/shard.yml
@@ -11,6 +11,7 @@ dependencies:
     github: geocrystal/geojson
   ring_area:
     github: geocrystal/ring_area
+    version: ">= 0.2.1"
 
 development_dependencies:
   ameba:
diff --git a/src/geojson/area.cr b/src/geojson/area.cr
index 1b6cd90..df762b2 100644
--- a/src/geojson/area.cr
+++ b/src/geojson/area.cr
@@ -5,7 +5,7 @@ module GeoJSON
     extend self
 
     # Given a Geometry object, return contained area as square meters.
-    def area(object : GeoJSON::Object) : Float64
+    def area(object : GeoJSON::Object) : Float32 | Float64
       case object
       when GeoJSON::Polygon
         polygon_area(object.coordinates)
@@ -22,7 +22,7 @@ module GeoJSON
       end
     end
 
-    private def polygon_area(coordinates) : Float64
+    private def polygon_area(coordinates) : Float32 | Float64
       coordinates.each_with_index.reduce(0.0) do |area, (ring, i)|
         if i == 0
           # exterior ring
@@ -34,10 +34,10 @@ module GeoJSON
       end
     end
 
-    private def ring_area(coordinates) : Float64
+    private def ring_area(coordinates) : Float32 | Float64
       coords = coordinates.map { |coordinate| [coordinate.longitude, coordinate.latitude] }
 
-      RingArea.ring_area(coords)
+      RingArea.ring_area(coords).to_meters
     end
   end
 end