diff --git a/collects/tests/web-server/pr/11125.rkt b/collects/tests/web-server/pr/11125.rkt
index 7d470fc19e..4e441ce475 100644
--- a/collects/tests/web-server/pr/11125.rkt
+++ b/collects/tests/web-server/pr/11125.rkt
@@ -5,62 +5,69 @@
          web-server/servlet-env
          tests/eli-tester)
 
-(define PORT 8999)
-
-(define (do-the-test PORT #:connection-close? connection-close?)
-  (define tc (make-thread-cell 0))
-  
-  (define (start req)
-    (thread-cell-set! tc (add1 (thread-cell-ref tc)))
-    (number->string (thread-cell-ref tc)))
-  
-  (define-values (pipe-read-p pipe-write-p)
-    (make-pipe))
-  
-  (define server-t
-    (thread
-     (λ ()
-       (parameterize ([current-output-port pipe-write-p])
-         (serve/servlet start
-                        #:launch-browser? #f
-                        #:connection-close? connection-close?
-                        #:quit? #f
-                        #:listen-ip #f
-                        #:port PORT
-                        #:servlet-path "/")))))
-  
-  ; Wait for server to start
-  (void (read-line pipe-read-p)
-        (read-line pipe-read-p))
-  
-  (define-values (http-read-p http-write-p)
-    (tcp-connect "localhost" PORT))
-  
-  (define (get-tc/err http-read-p http-write-p)
-    (with-handlers
-        ([exn?
-          (λ (x)
-            (define-values (new-http-read-p new-http-write-p)
-              (tcp-connect "localhost" PORT))
-            (set! http-read-p new-http-read-p)
-            (set! http-write-p new-http-write-p)
-            (get-tc http-read-p http-write-p))])
-      (get-tc http-read-p http-write-p)))
-  
-  (define (get-tc http-read-p http-write-p)
-    (fprintf http-write-p "GET / HTTP/1.1\r\n\r\n")
-    (flush-output http-write-p)
-    
-    (read-line http-read-p)
-    (read-headers http-read-p)
-    (string->number (string (read-char http-read-p))))
-  
+(define (do-the-test #:connection-close? connection-close?)
+  (define cust (make-custodian))
   (begin0
-    (list (get-tc/err http-read-p http-write-p)
-          (get-tc/err http-read-p http-write-p))
-    
-    (kill-thread server-t)))
-
-(test
- (do-the-test PORT #:connection-close? #f) => (list 1 2)
- (do-the-test (add1 PORT) #:connection-close? #t) => (list 1 1))
+    (parameterize ([current-custodian cust])
+      (define tc (make-thread-cell 0))
+      
+      (define (start req)
+        (thread-cell-set! tc (add1 (thread-cell-ref tc)))
+        (number->string (thread-cell-ref tc)))
+      
+      (define-values (pipe-read-p pipe-write-p)
+        (make-pipe))
+      
+      (define server-t
+        (thread
+         (λ ()
+           (parameterize ([current-output-port pipe-write-p])
+             (serve/servlet start
+                            #:launch-browser? #f
+                            #:connection-close? connection-close?
+                            #:quit? #f
+                            #:listen-ip #f
+                            #:port 0
+                            #:servlet-path "/")))))
+      
+      ; Wait for server to start
+      (define port-embedded-line (read-line pipe-read-p))
+      (match-define (regexp #rx"Your Web application is running at http://localhost:([0-9]+)\\." 
+                            (list _ port-string))
+                    port-embedded-line)
+      (define port (string->number port-string))
+      (void (read-line pipe-read-p))
+      
+      (define-values (http-read-p http-write-p)
+        (tcp-connect "localhost" port))
+      
+      (define (get-tc/err http-read-p http-write-p)
+        (with-handlers
+            ([exn?
+              (λ (x)
+                (define-values (new-http-read-p new-http-write-p)
+                  (tcp-connect "localhost" port))
+                (set! http-read-p new-http-read-p)
+                (set! http-write-p new-http-write-p)
+                (get-tc http-read-p http-write-p))])
+          (get-tc http-read-p http-write-p)))
+      
+      (define (get-tc http-read-p http-write-p)
+        (fprintf http-write-p "GET / HTTP/1.1\r\n\r\n")
+        (flush-output http-write-p)
+        
+        (read-line http-read-p)
+        (read-headers http-read-p)
+        (string->number (string (read-char http-read-p))))
+      
+      (begin0
+        (list (get-tc/err http-read-p http-write-p)
+              (get-tc/err http-read-p http-write-p))
+        
+        (kill-thread server-t)))
+    (custodian-shutdown-all cust)))
+  
+  (test
+   (do-the-test #:connection-close? #f) => (list 1 2)
+   (do-the-test #:connection-close? #t) => (list 1 1))
+  
\ No newline at end of file