“We need your product to run on this Operating System”. Unfortunately, that OS wasn’t supported yet. The prospect was keen on buying, but this requirement definitely stood in the way of closing a deal. 
I usually would mark this as Closed Lost because of requirements I couldn’t fulfill. This time, however, I figured it’s time to try something new. 

I got back to them with a proposal: “We don’t support this particular Operating System at the moment. But it’s on the product roadmap. We start working on this right away in exchange for a development fee”. They let me know that they needed to get back to me on this proposal. I was feeling confident about my proposal. They would say yes. 

But then, something unexpected happened. Instead of insisting on the original requirement, the prospect started discussions internally if it wasn’t possible to also use a different Operating System. An OS they usually don’t use and support. 

What had happened? Price can be a powerful tool in negotiation. It opened up a new perspective: They might not want to spend the additional thousands of dollars on this development effort, therefore it might be cheaper to just use our recommended Operating System.
I was serious about my offer. If they had said yes, I would have pushed forward this effort internally on my side. 

But this outcome was good too, because they made a decision. And that’s the job of Sales people: Enabling their prospects and customers to make decisions.