diff --git a/typed-racket-lib/typed-racket/base-env/prims-contract.rkt b/typed-racket-lib/typed-racket/base-env/prims-contract.rkt
index e2b2aebd..fc357bd3 100644
--- a/typed-racket-lib/typed-racket/base-env/prims-contract.rkt
+++ b/typed-racket-lib/typed-racket/base-env/prims-contract.rkt
@@ -343,7 +343,7 @@
             (define existing-ty-ctc (syntax-local-lift-expression
                                      (make-contract-def-rhs/from-typed existing-ty-id #f #f)))
             (define (store-existing-type existing-type)
-              (cast-table-set! existing-ty-id existing-type))
+              (cast-table-set! existing-ty-id (datum->syntax #f existing-type #'v)))
             (define (check-valid-type _)
               (define type (parse-type #'ty))
               (define vars (fv type))