Derby defender Paul Boertien has returned to Pride Park by mutual consent after completing a short loan spell with Chesterfield. The 28-year-old joined the Spireites on loan in March and played four games.
Caretaker boss Lee Richardson told Chesterfield's website: "For the last two games of the season I am not able to guarantee Paul a place in the side.
"As his main objective was to get some match practice I fully understand his wish to return to his club."