diff --git a/pkgs/racket-test-core/tests/racket/port.rktl b/pkgs/racket-test-core/tests/racket/port.rktl
index 1d84f275a9..6b55a1c255 100644
--- a/pkgs/racket-test-core/tests/racket/port.rktl
+++ b/pkgs/racket-test-core/tests/racket/port.rktl
@@ -95,6 +95,51 @@
 (test #t string-port? (open-output-bytes))
 (test #t string-port? (open-output-string))
 
+;; concurrent close on input fails
+(let ()
+  (define-values (i o) (make-pipe))
+  (thread (lambda ()
+            (sync (system-idle-evt))
+            (close-input-port i)))
+  (err/rt-test
+   (peek-bytes-avail! (make-bytes 10) 0 #f i)
+   exn:fail?))
+
+;; concurrent close on input triggers progress
+(let ()
+  (define-values (i o) (make-pipe))
+  (thread (lambda ()
+            (sync (system-idle-evt))
+            (close-input-port i)))
+  (test 0 peek-bytes-avail! (make-bytes 10) 0 (port-progress-evt i) i))
+
+;; concurrent close on output fails
+(let ()
+  (define-values (i o) (make-pipe 4096))
+  (thread (lambda ()
+            (sync (system-idle-evt))
+            (close-output-port o)))
+  (err/rt-test
+   (let loop ()
+     (write-bytes #"hello" o)
+     (loop))
+   exn:fail?))
+
+;; concurrent close of input unblocks limited output
+(let ()
+  (define-values (i o) (make-pipe 4096))
+  (define done? #f)
+  (thread (lambda ()
+            (sync (system-idle-evt))
+            (set! done? #t)
+            (close-input-port i)))
+
+  ;; Shouldn't get stuck:
+  (let loop ()
+    (write-bytes #"hello" o)
+    (unless done?
+      (loop))))
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Based on the Racket manual...
 
diff --git a/racket/src/io/demo.rkt b/racket/src/io/demo.rkt
index 2ad8e2722a..7294ad6a0b 100644
--- a/racket/src/io/demo.rkt
+++ b/racket/src/io/demo.rkt
@@ -15,6 +15,22 @@
 (path->string (current-directory))
 (set-string->number?! string->number)
 
+(let ()
+  (define-values (i o) (make-pipe 4096))
+
+  (define done? #f)
+
+  (thread (lambda ()
+            (sync (system-idle-evt))
+            (set! done? #t)
+            (close-input-port i)))
+
+  ;; Should error:
+  (let loop ()
+    (write-bytes #"hello" o)
+    (unless done?
+      (loop))))
+
 (define-syntax-rule (test expect rhs)
   (let ([e expect]
         [v rhs])
diff --git a/racket/src/io/port/pipe.rkt b/racket/src/io/port/pipe.rkt
index b82be0e8b7..330ca30f4f 100644
--- a/racket/src/io/port/pipe.rkt
+++ b/racket/src/io/port/pipe.rkt
@@ -284,7 +284,9 @@
        (when input-ref
          (slow-mode!)
          (set! input-ref #f)
-         (progress!))))]
+         (progress!)
+         (check-input-unblocking)
+         (check-output-unblocking))))]
 
   [get-progress-evt
    (lambda ()
@@ -433,6 +435,9 @@
          (cond
            [(fx= src-start src-end) ;; => flush
             0]
+           [(not input-ref)
+            ;; No input end => accept all bytes
+            (fx- src-end src-start)]
            [(and (end . fx>= . start)
                  (end . fx< . top-pos))
             (define amt (apply-limit (fxmin (fx- top-pos end)
@@ -486,7 +491,8 @@
        (when output-ref
          (slow-mode!)
          (set! output-ref #f)
-         (check-input-unblocking))))])
+         (check-input-unblocking)
+         (check-output-unblocking))))])
 
 ;; ----------------------------------------
 
@@ -531,8 +537,6 @@
 
 ;; ----------------------------------------
 
-;; Note: a thread blocked on writing to a limited pipe cannot be GCed
-;; due to the use of `replace-evt`.
 (struct pipe-write-poller (d)
   #:property
   prop:evt
@@ -541,7 +545,9 @@
      (with-object pipe-data (pipe-write-poller-d pwp)
        (sync-both)
        (cond
-         [(not (output-full?))
+         [(or (not (output-full?))
+              (not input-ref)
+              (not output-ref))
           (values (list pwp) #f)]
          [else
           (unless write-ready-sema
@@ -560,7 +566,9 @@
      (with-object pipe-data (pipe-read-poller-d prp)
        (sync-both)
        (cond
-         [(not (input-empty?))
+         [(or (not (input-empty?))
+              (not output-ref)
+              (not input-ref))
           (values (list 0) #f)]
          [else
           (unless read-ready-sema