NodeJS MongoDB Update inc

Question

I'm having trouble using the $inc operator to update my mongodb collection. To make things simpler, I made a test collection.

My code:

collection.update({field1: 'text'}, { $inc: { items: 5 } }, function (error, result) {
    if (error) reject(error);
    else resolve(result);
});

My collection:

/* 1 */
{
    "_id" : ObjectId("55d2d56a931d867cfeeba4cb"),
    "field1" : "text",
    "items" : 0
}

The update operation returns no errors, response is OK with 0 updated documents.

What am I doing wrong?

P.S. My mongodb library version is 2.0.39

[edit] I've also tried updateOne method since I saw update is deprecated in version 2, same result though