Anyways, I came today to ask another question related to bags

A few weeks ago, I bought a small shoulder bag ( an 10 inch iPad bag ) and done a few modifications on it. Now, I need to do soemthing about the shoulder strap. It is about 1.5 inches wide, and is so smooth. It always slides off my shoulder. I need to attach something to it that makes it slip-proof.

Does any bag sompany sell such a thing ?

The strap is not removeable. It is sewn into the bag on one end, so I can't change it.