diff --git a/collects/tests/racket/stress/fuzz.rkt b/collects/tests/racket/stress/fuzz.rkt
index ad88974e1c..99ca3f99be 100644
--- a/collects/tests/racket/stress/fuzz.rkt
+++ b/collects/tests/racket/stress/fuzz.rkt
@@ -1,54 +1,37 @@
 #lang racket
 
-(require racket/runtime-path)
+(require setup/dirs)
 
-(define (flip n bit)
-  (define new-bit (expt 2 bit))
-  (bitwise-xor new-bit n))
-
-(define (flip-file bs idx)
-  (define-values (byte bit) (quotient/remainder idx 8))  
+(define (flip-bit bs idx)
+  (define-values [byte bit] (quotient/remainder idx 8))
   (define val (bytes-ref bs byte))
-  (bytes-set! bs byte (flip val bit)))
+  (bytes-set! bs byte (bitwise-xor (expt 2 bit) val)))
 
 (define (run-file bs)
   (eval (parameterize ([read-accept-compiled #t])
           (with-input-from-bytes bs read))))
 
-
-(define sd #f)
-(define fl #f)
-(define dir #f)
-
-(define (run fname [seed (or sd (+ 1 (random (expt 2 30))))])
-  (printf "DrDr Ignore! random-seed ~s\n" seed)
-  (printf "name: ~a\n" fname)
+(define (run fname seed0)
+  (define seed (or seed0 (+ 1 (random (expt 2 30)))))
+  (printf "seed: ~s\nname: ~a\n" seed fname)
   (flush-output)
   (random-seed seed)
-  (define bs (file->bytes fname))
+  (define bs  (file->bytes fname))
   (define len (* 8 (bytes-length bs)))
-  (for ([i (in-range (quotient len 10000))])
-    (flip-file bs (random len)))
-  (with-handlers ([void void])
-    (run-file bs)))
+  (for ([i (in-range (quotient len 10000))]) (flip-bit bs (random len)))
+  (with-handlers ([void void]) (run-file bs)))
 
-
-(define collects-dir 
-  (find-executable-path (find-system-path 'exec-file)
-			(find-system-path 'collects-dir)))
-
-(command-line 
- #:once-each
- ["-s" seed "random seed" (set! sd (string->number seed))]
- #:once-any
- ["-f" file "filename to run"
-  (set! fl file)]
- ["-d" dir* "dir to run" (set! dir dir*)]
- ["-c" "run over all collections"
- (set! dir collects-dir)]
-  #:args () (void))
-
-(cond [fl (run fl)]
-      [dir (for ([p (in-directory dir)]
-		 #:when (regexp-match "\\.zo" p))
-	      (run p))])
+(let ([seed #f] [file #f] [dir #f])
+  (command-line
+   #:once-each
+   ["-s" seed "random seed" (set! seed (string->number seed))]
+   #:once-any
+   ["-f" file "filename to run"     (set! file file)]
+   ["-d" dir* "dir to run"          (set! dir dir*)]
+   ["-c" "run over all collections" (set! dir (find-collects-dir))]
+   #:args () (void))
+  (cond [file (run file seed)]
+        [dir (for ([p (in-directory dir)]
+                   #:when (regexp-match #rx"\\.zo" p))
+               (run p seed))]
+        [else (printf "Nothing to do.\n")]))