Maclean has played three games since his arrival at the Kassam Stadium, scoring one goal, and is delighted to have prolonged his stay with the Us.
"I`m really happy to be staying at the club for another month," he told United`s official website.
"I`ve really enjoyed my time with Oxford so far and everybody has made me feel very welcome. Hopefully I can score a few more goals between now and January and help them push their way back up the table."
Manager Chris Wilder is also happy with the loan extension. He added: "Everyone has been impressed with Steve since he arrived. He has obvious ability and he`s shown the quality he has in the three games he`s played for us so we`re delighted that he`s agreed to extend his stay."
The emergency loan window may have closed last Thursday, but Oxford have been able to take advantage of a seven-day period in which to extend existing deals.
Source: PA
