Thank you all for your thoughtful responses! Considering the potential client has also asked for some other contract changes that would increase my liability to them, I've decided to stand firm and not give in to any of their contract change requests. We've been working on getting a deal together for 6 weeks now and I've found them quite inexperienced with technical matters so far. I think this translates into a lack of trust towards me, though I don't get the feeling there's any malice or ill-will behind it. So if they insist on their proposed changes to the contract, I will happily walk away. Thanks again for your thoughts!