The former Stockport player told BBC Radio Humberside: "A permanent move would've been great and given me a permanent chance in the Championship.
"Maybe it'll get extended in January. I don't see why not if I'm happy here."
McNulty is a former Wrexham trainee who has also had spells at Macclesfield and Stockport during his seven-year career.
I was happy last time so hope there'll be an extension
Scunthorpe loan defender Jim McNulty
He impressed Iron manager Nigel Adkins towards the end of last season, when he started two games and made a substitute appearance.
And the full-back says his previous stint played a big part in him wanting to return again this season: "I expect to be happy here because I was happy with my short stay last time so I would hope there'll be an extension."
Source: BBC Sport
Source: BBC Sport