diff --git a/db/mailchimp.js b/db/mailchimp.js
new file mode 100644
index 0000000..55485fb
--- /dev/null
+++ b/db/mailchimp.js
@@ -0,0 +1,19 @@
+// Execute this script only if you're upgrading to v0.2.2 or later.
+// Not required for a fresh db.
+
+use mailchimp;
+
+// Add type data to preference fields of the installations
+var cursor = db.getCollection('installations').find({});
+while (cursor.hasNext()) {
+    var obj1 = cursor.next();
+    var prefs = obj1.preferences;
+    if (prefs) {
+        prefs.forEach(function (item) {
+            item.values.forEach(function (vals) {
+                vals['type'] = 'string';
+            });
+        });
+    }
+    db.getCollection('installations').update({'_id': obj1._id}, obj1);
+}