diff --git a/pkgs/racket-doc/scribblings/reference/format.scrbl b/pkgs/racket-doc/scribblings/reference/format.scrbl
index 13761200e6..7a240c8307 100644
--- a/pkgs/racket-doc/scribblings/reference/format.scrbl
+++ b/pkgs/racket-doc/scribblings/reference/format.scrbl
@@ -5,7 +5,8 @@
           "mz.rkt"
           (for-label racket/contract
                      racket/math
-                     racket/format))
+                     racket/format
+                     racket/string))
 
 @(begin
   (define the-eval (make-base-eval))