diff --git a/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/base-env/extra-procs.rkt b/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/base-env/extra-procs.rkt
index d86fffc9..29e1a64b 100644
--- a/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/base-env/extra-procs.rkt
+++ b/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/base-env/extra-procs.rkt
@@ -4,7 +4,8 @@
 (define-syntax assert
   (syntax-rules ()
     ((assert v)
-     (or v (error (format "Assertion failed on ~v" v))))
+     (let ([val v])
+       (or val (error (format "Assertion failed on ~v" val)))))
     ((assert v pred)
      (let ((val v))
        (if ((#%expression pred) val)