diff --git a/geojson/utils.py b/geojson/utils.py
index a59b16c..58f29e1 100644
--- a/geojson/utils.py
+++ b/geojson/utils.py
@@ -119,15 +119,8 @@ def map_geometries(func, obj):
         geoms = [func(geom) if geom else None for geom in obj['geometries']]
         return {'type': obj['type'], 'geometries': geoms}
     elif obj['type'] == 'Feature':
-        geom = func(obj['geometry']) if obj['geometry'] else None
-        result = {
-            'type': obj['type'],
-            'geometry': geom,
-            'properties': obj['properties'],
-        }
-        if 'id' in obj:
-            result['id'] = obj['id']
-        return result
+        obj['geometry'] = func(obj['geometry']) if obj['geometry'] else None
+        return obj
     elif obj['type'] == 'FeatureCollection':
         feats = [map_geometries(func, feat) for feat in obj['features']]
         return {'type': obj['type'], 'features': feats}
diff --git a/tests/test_coords.py b/tests/test_coords.py
index b327c4c..1405199 100644
--- a/tests/test_coords.py
+++ b/tests/test_coords.py
@@ -1,7 +1,7 @@
 import unittest
 
 import geojson
-from geojson.utils import coords, map_coords, map_tuples
+from geojson.utils import coords, map_coords
 
 
 class CoordsTestCase(unittest.TestCase):
@@ -67,23 +67,14 @@ def test_map_multipolygon(self):
         self.assertEqual(result['coordinates'][-1][-1][-1], (23.18, -34.29))
 
     def test_map_feature(self):
-        f = geojson.Feature(
-            id='0',
-            geometry=geojson.Point([-77.1291115237051, 38.7993076720178]),
-            properties={
-                'name': 'Van Dorn Street',
-                'marker-col': '#0000ff',
-                'marker-sym': 'rail-metro',
-                'line': 'blue',
-            },
+        g = geojson.Feature(
+            id='123',
+            geometry=geojson.Point([-115.81, 37.24])
         )
-        result = map_tuples(lambda t: t, f)
+        result = map_coords(lambda x: x, g)
         self.assertEqual(result['type'], 'Feature')
-        self.assertEqual(result['id'], '0')
-        self.assertEqual(
-            result['geometry']['coordinates'],
-            (-77.1291115237051, 38.7993076720178)
-        )
+        self.assertEqual(result['id'], '123')
+        self.assertEqual(result['geometry']['coordinates'], (-115.81, 37.24))
 
     def test_map_invalid(self):
         with self.assertRaises(ValueError):