Coventry have signed defender Paul Watson and midfielder Andy Impey on non-contract terms.
Impey was released by Forest after they were relegated
The pair had both been training with Micky Adams' squad since pre-season and can now feature in first-team action.
Watson, 30, was released by Brighton - where he was signed by Adams in 1999 - in the summer.
Much-travelled winger Impey, 33, was released by Nottingham Forest after their relegation last season, and also played under Adams at Leicester.