"Greg has been performing well for Telford and they are very pleased with his contribution in these early stages of the season," Derby boss Nigel Clough told the club's official website.
"It is a good experience for him to be playing week-in week-out and Greg is enjoying himself, which is important." Mills has scored three goals in six appearances this season for Telford, who are currently second in the table behind Alfreton Town.
Source: PA