diff --git a/dragonfly/model.py b/dragonfly/model.py
index bc902eea..f94bc1db 100644
--- a/dragonfly/model.py
+++ b/dragonfly/model.py
@@ -537,7 +537,7 @@ def to_geojson(self, location, point=Point2D(0, 0), folder=None, tolerance=0.01)
             feature_dict['properties']['floor_area'] = bldg.floor_area
             feature_dict['properties']['footprint_area'] = \
                 sum((face.area for face in footprint))
-            feature_dict['properties']['id'] = i
+            feature_dict['properties']['id'] = str(i + 1)
             feature_dict['properties']['name'] = bldg.name
             feature_dict['properties']['number_of_stories'] = bldg.story_count
             feature_dict['properties']['type'] = 'Building'
diff --git a/tests/geojson/NewDevelopment.geojson b/tests/geojson/NewDevelopment.geojson
index 798602ef..118c46f2 100644
--- a/tests/geojson/NewDevelopment.geojson
+++ b/tests/geojson/NewDevelopment.geojson
@@ -41,7 +41,7 @@
                 "building_type": "Mixed use",
                 "floor_area": 600.0,
                 "footprint_area": 200.0,
-                "id": 0,
+                "id": "1",
                 "name": "ResidenceBuilding",
                 "number_of_stories": 3,
                 "type": "Building",
@@ -81,7 +81,7 @@
                 "building_type": "Mixed use",
                 "floor_area": 200.0,
                 "footprint_area": 200.0,
-                "id": 1,
+                "id": "2",
                 "name": "RetailBuildingBig",
                 "number_of_stories": 1,
                 "type": "Building",
@@ -185,7 +185,7 @@
                 "building_type": "Mixed use",
                 "floor_area": 1625.0,
                 "footprint_area": 325.0,
-                "id": 2,
+                "id": "3",
                 "name": "OfficeBuilding",
                 "number_of_stories": 5,
                 "type": "Building",