diff --git a/lisp/help.el b/lisp/help.el
index 795f7e74d8b..df055d602fe 100644
--- a/lisp/help.el
+++ b/lisp/help.el
@@ -1013,8 +1013,7 @@ Otherwise, return a new string (without any text properties)."
         (insert string)
         (goto-char (point-min))
         (while (< (point) (point-max))
-          (let ((standard-output (current-buffer))
-                (orig-point (point))
+          (let ((orig-point (point))
                 end-point active-maps
                 close generate-summary)
             (cond
diff --git a/test/lisp/help-tests.el b/test/lisp/help-tests.el
index 079b1114a81..b6dffb2a405 100644
--- a/test/lisp/help-tests.el
+++ b/test/lisp/help-tests.el
@@ -361,6 +361,26 @@ C-b		undefined
 
 ")))))
 
+(defvar help-tests--was-in-buffer nil)
+
+(ert-deftest help-substitute-command-keys/menu-filter-in-correct-buffer ()
+  "Evaluate menu-filter in the original buffer.  See Bug#39149."
+  (unwind-protect
+      (progn
+        (define-key global-map (kbd "C-c C-l r")
+          `(menu-item "2" identity
+                      :filter ,(lambda (cmd)
+                                 (setq help-tests--was-in-buffer
+                                       (current-buffer))
+                                 cmd)))
+        (with-temp-buffer
+          (substitute-command-keys "\\[identity]")
+          (should (eq help-tests--was-in-buffer
+                      (current-buffer)))))
+    (setq help-tests--was-in-buffer nil)
+    (define-key global-map (kbd "C-c C-l r") nil)
+    (define-key global-map (kbd "C-c C-l") nil)))
+
 (provide 'help-tests)
 
 ;;; help-tests.el ends here