diff --git a/racket/src/io/port/custom-input-port.rkt b/racket/src/io/port/custom-input-port.rkt
index a9a377aeff..cf0edef1bc 100644
--- a/racket/src/io/port/custom-input-port.rkt
+++ b/racket/src/io/port/custom-input-port.rkt
@@ -260,40 +260,41 @@
          (make-buffer-mode user-buffer-mode)))
 
   (cond
-   [user-peek-in
-    (make-core-input-port
-     #:name name
-     #:self #f
-     #:read-in
-     (if (input-port? user-read-in)
-         user-read-in
-         read-in)
-     #:peek-in
-     (if (input-port? user-peek-in)
-         user-peek-in
-         peek-in)
-     #:byte-ready
-     (if (input-port? user-peek-in)
-         user-peek-in
-         byte-ready)
-     #:close close
-     #:get-progress-evt (and user-get-progress-evt get-progress-evt)
-     #:commit (and user-commit commit)
-     #:get-location get-location
-     #:count-lines! count-lines!
-     #:init-offset init-offset
-     #:file-position file-position
-     #:buffer-mode buffer-mode)]
-   [else
-    (define-values (port buffer-flusher)
-      (open-input-peek-via-read
-       #:name name
-       #:self #f
-       #:read-in read-in
-       #:close close
-       #:get-location get-location
-       #:count-lines! count-lines!
-       #:init-offset init-offset
-       #:file-position file-position
-       #:alt-buffer-mode buffer-mode))
-    port]))
+    [user-peek-in
+     (new core-input-port
+          #:override
+          ([read-in (if (input-port? user-read-in)
+                        user-read-in
+                        read-in)]
+           [peek-in (if (input-port? user-peek-in)
+                        user-peek-in
+                        peek-in)]
+           [byte-ready (if (input-port? user-peek-in)
+                           user-peek-in
+                           byte-ready)]
+           [close close]
+           [get-progress-evt (and user-get-progress-evt get-progress-evt)]
+           [commit (and user-commit commit)]
+           [get-location get-location]
+           [count-lines! count-lines!]
+           [file-position file-position]
+           [buffer-mode buffer-mode])
+          [name name]
+          [offset init-offset])]
+    [else
+     (new peek-via-read-input-port
+          #:override
+          ([read-in/inner read-in]
+           [close (values
+                   (lambda (self)
+                     (close self)
+                     (send peek-via-read-input-port self close-peek-buffer)))]
+           [get-location  get-location]
+           [count-lines! count-lines!]
+           [file-position file-position]
+           [buffer-mode (or buffer-mode
+                            (case-lambda
+                              [(self) (send peek-via-read-input-port self default-buffer-mode)]
+                              [(self mode) (send peek-via-read-input-port self default-buffer-mode mode)]))])
+          [name name]
+          [offset init-offset])]))
diff --git a/racket/src/io/port/nowhere.rkt b/racket/src/io/port/nowhere.rkt
index f149a7a408..9620150a50 100644
--- a/racket/src/io/port/nowhere.rkt
+++ b/racket/src/io/port/nowhere.rkt
@@ -1,14 +1,15 @@
 #lang racket/base
-(require "output-port.rkt")
+(require "../common/class.rkt"
+         "output-port.rkt")
 
 (provide open-output-nowhere)
 
+(class nowhere-output-port #:extends core-output-port
+  (override
+    [write-out-special
+     (lambda (any no-block/buffer? enable-break?)
+       #t)]))
+
 (define (open-output-nowhere)
-  (make-core-output-port #:name 'nowhere
-                         #:self #f
-                          #:evt always-evt
-                          #:write-out (lambda (self bstr start-k end-k no-block/buffer? enable-break? copy?)
-                                        (- end-k start-k))
-                          #:close void
-                          #:write-out-special (lambda (self any no-block/buffer? enable-break?)
-                                                #t)))
+  (new nowhere-output-port
+       [name 'nowhere]))
diff --git a/racket/src/io/port/output-port.rkt b/racket/src/io/port/output-port.rkt
index 90af0aefe7..7f2efab6f3 100644
--- a/racket/src/io/port/output-port.rkt
+++ b/racket/src/io/port/output-port.rkt
@@ -67,7 +67,7 @@
    ;; The return values are the same as documented for
    ;; `make-output-port`.
    [write-out (lambda (bstr start-k end-k no-block/buffer? enable-break? copy?)
-                (- start-k end-k))]
+                (- end-k start-k))]
 
    ;; #f or (any no-block/buffer? enable-break? -*> boolean?)
    ;; Called in atomic mode.
diff --git a/racket/src/io/port/peek-via-read-port.rkt b/racket/src/io/port/peek-via-read-port.rkt
index 4ffa902513..24486c6a67 100644
--- a/racket/src/io/port/peek-via-read-port.rkt
+++ b/racket/src/io/port/peek-via-read-port.rkt
@@ -41,7 +41,13 @@
 
    [buffer-adjust-pos
     (lambda (i)
-      (- i (fx- end-pos (if buffer buffer-pos pos))))])
+      (- i (fx- end-pos (if buffer buffer-pos pos))))]
+
+   ;; in atomic mode
+   [default-buffer-mode
+    (case-lambda
+      [() buffer-mode]
+      [(mode) (set! buffer-mode mode)])])
 
   (private
     ;; in atomic mode
@@ -218,8 +224,8 @@
     ;; in atomic mode
     [buffer-mode
      (case-lambda
-       [(self) buffer-mode]
-       [(self mode) (set! buffer-mode mode)])]
+       [() (default-buffer-mode)]
+       [(mode) (default-buffer-mode mode)])]
 
     ;; in atomic mode
     [close