While trying to scribble some documentation, I came across what seems to be a bug involving contracts and scribble's interaction form. my-module.scrbl: #lang scribble/manual @(require scribble/eval) When I introduce contracts into "my-module.rkt", the following lines... @(define my-eval (make-eval-factory (list "my-module.rkt"))) @(interaction #:eval (my-eval) (my-thunk)) ... produces the error message: namespace-attach-module: a different module with the same name is already in the destination namespace, for name: "C:\Program Files\Racket\collects\racket\contract.rkt" my-module.rkt: #lang racket/base (require racket/contract) (provide/contract [my-thunk (-> void?)]) (define (my-thunk) (display (format "Hi there, Racket fans!~n"))) If I do not use contracts in my-module.rkt, then the scribbling works fine. If I do, then evaluating (my-eval) generates the error. What up?