diff --git a/migrations/20131117_remove_undefined_pets.js b/migrations/20131117_remove_undefined_pets.js
new file mode 100644
index 0000000000..f908621a75
--- /dev/null
+++ b/migrations/20131117_remove_undefined_pets.js
@@ -0,0 +1,12 @@
+// once and for all!
+
+db.users.find({'items.pets':{$exists:1}},{'items.pets':1}).forEach(function(user){
+  _.reduce(user.items.pets, function(m,v,k){
+    if (!k.indexOf('undefined')) m.push(k);
+    return m;
+  }, []).forEach(function(key){
+    delete user.items.pets[key];
+  })
+
+  db.users.update({_id:user._id}, { $set:{'items.pets':user.items.pets} });
+});