diff --git a/racket/collects/setup/unixstyle-install.rkt b/racket/collects/setup/unixstyle-install.rkt
index 7536d02a00..bc338cfe19 100644
--- a/racket/collects/setup/unixstyle-install.rkt
+++ b/racket/collects/setup/unixstyle-install.rkt
@@ -410,6 +410,9 @@
      (define (ftime file)
        (and (file-exists? file) (file-or-directory-modify-seconds file)))
      (let* ([src (cpath "config.rktd")])
+       (define link-shared?
+         ;; before "config.rktd" is potentially modified:
+         (eq? 'shared (cross-system-type 'link)))
        (printf "Rewriting configuration file at: ~a...\n" src)
        (define old (or (and (file-exists? src)
                             (call-with-input-file src read))
@@ -423,7 +426,7 @@
            (printf ";; generated by unixstyle-install\n")
            (printf "#hash(\n")
            (out! 'doc-dir (dir: 'doc))
-           (when (eq? 'shared (cross-system-type 'link)) ; never true for now
+           (when link-shared? ; never true for now
              (out! 'dll-dir (dir: 'lib)))
            (out! 'lib-dir (dir: 'librkt))
            (out! 'pkgs-dir (dir: 'pkgs))