The 28-year-old Frenchman has agreed a switch to The Den until January 2 having found first-team opportunities limited with Forest this season.
Lions assistant boss Mick Harford told the club website: "Shaun left us last week and we wanted some competition in midfield.
"Guy is big, strong and athletic, and that's exactly the type of player we've been looking for."
- Sports & Recreation
- Shaun Derry