The 18 year old has scored 16 goals in 22 games for Coventry since arriving from Newcastle last summer on a deal that due to expire on 16 January.
"We have to be cautious," Mowbray told BBC Coventry and Warwickshire.
"Until there's a new deal signed, we're just happy we've got him for the period we have - hopefully he'll stay."
Despite Magpies head coach Steve McClaren indicating that he is happy to see the striker stay at the Ricoh Arena, Mowbray is not taking anything for granted.
"The deal's yet to be rubber stamped as far as I'm concerned," Mowbray said.
"I saw Steve's comments but until everything's done, it's never done."
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!