diff --git a/src/c3nav/mapdata/migrations/0002_fix_broken_spaces.py b/src/c3nav/mapdata/migrations/0002_fix_broken_spaces.py
new file mode 100644
index 00000000..cfd212ba
--- /dev/null
+++ b/src/c3nav/mapdata/migrations/0002_fix_broken_spaces.py
@@ -0,0 +1,23 @@
+# Generated by Django 2.1.4 on 2018-12-10 22:38
+
+from django.db import migrations
+from shapely.geometry import Polygon
+
+
+def fix_broken_spaces(apps, schema_editor):
+    Space = apps.get_model('mapdata', 'Space')
+    for space in Space.objects.all():
+        geometry = space.geometry
+        space.geometry = Polygon(shell=geometry.exterior)
+        space.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mapdata', '0001_squashed_2018'),
+    ]
+
+    operations = [
+        migrations.RunPython(fix_broken_spaces, migrations.RunPython.noop)
+    ]