diff --git a/pkgs/racket-pkgs/racket-doc/scribblings/inside/ports.scrbl b/pkgs/racket-pkgs/racket-doc/scribblings/inside/ports.scrbl
index 210651f8e8..377fc34bf1 100644
--- a/pkgs/racket-pkgs/racket-doc/scribblings/inside/ports.scrbl
+++ b/pkgs/racket-pkgs/racket-doc/scribblings/inside/ports.scrbl
@@ -800,8 +800,11 @@ is created, it remains findable via @cpp{scheme_fd_to_semaphore} for a
 particular read/write mode as long as @var{fd} has not become ready in
 the read/write mode since the creation of the semaphore, or unless
 @cpp{MZFD_REMOVE} has been used to remove the registered semaphore.
-The @var{is_socket} argument indicates whether @var{fd} is a socket
-or a filesystem descriptor (and the difference matters only for Windows).
+The @var{is_socket} argument indicates whether @var{fd} is a socket or
+a filesystem descriptor; the difference matters for Windows, and it
+matters for BSD-based platforms where sockets are always supported and
+other file descriptors are tested for whether they correspond to a
+directory or regular file.
 
 The @var{mode} argument is one of the following:
 
@@ -824,6 +827,19 @@ The @var{mode} argument is one of the following:
  @item{@cpp{MZFD_REMOVE} (= @cpp{5}) --- removes all recorded
        semaphores for @var{fd} (unregistering a poll with the
        operating system) and returns @cpp{NULL}.}
+
+ @item{@cpp{MZFD_CREATE_VNODE} (= @cpp{6}) --- creates or finds a
+       semaphore to reflect whether @var{fd} changes; on some
+       platforms, @cpp{MZFD_CREATE_VNODE} is the same as
+       @cpp{MZFD_CREATE_READ}; on other platforms, only one or the
+       other can be used on a given file descriptor.}
+
+ @item{@cpp{MZFD_CHECK_VNODE} (= @cpp{7}) --- like @cpp{MZFD_CHECK_READ},
+       but to find a semaphore recorded via @cpp{MZFD_CREATE_VNODE}.}
+
+ @item{@cpp{MZFD_REMOVE_VNODE} (= @cpp{8}) --- like @cpp{MZFD_REMOVE},
+       but to remove a semaphore recorded via @cpp{MZFD_CREATE_VNODE}.}
+
 ]}
 
 
diff --git a/racket/src/racket/include/scheme.h b/racket/src/racket/include/scheme.h
index 439c12f91e..c19ae77ac2 100644
--- a/racket/src/racket/include/scheme.h
+++ b/racket/src/racket/include/scheme.h
@@ -2107,6 +2107,7 @@ extern Scheme_Extension_Table *scheme_extension_table;
 #define MZFD_REMOVE       5
 #define MZFD_CREATE_VNODE 6
 #define MZFD_CHECK_VNODE  7
+#define MZFD_REMOVE_VNODE 8
 
 /*========================================================================*/
 
diff --git a/racket/src/racket/src/port.c b/racket/src/racket/src/port.c
index 3bb34d51ca..7b4a6eb682 100644
--- a/racket/src/racket/src/port.c
+++ b/racket/src/racket/src/port.c
@@ -6152,7 +6152,7 @@ void scheme_filesystem_change_evt_cancel(Scheme_Object *evt, void *ignored_data)
       fc->fd = 0;
     }
 # else
-    (void)scheme_fd_to_semaphore(fc->fd, MZFD_REMOVE, 0);
+    (void)scheme_fd_to_semaphore(fc->fd, MZFD_REMOVE_VNODE, 0);
     scheme_close_file_fd(fc->fd);
     scheme_post_sema_all(fc->sema);
 # endif
diff --git a/racket/src/racket/src/thread.c b/racket/src/racket/src/thread.c
index 5f82e91dd1..68f72398ea 100644
--- a/racket/src/racket/src/thread.c
+++ b/racket/src/racket/src/thread.c
@@ -3507,7 +3507,8 @@ Scheme_Object *scheme_fd_to_semaphore(intptr_t fd, int mode, int is_socket)
   if (!v && ((mode == MZFD_CHECK_READ)
              || (mode == MZFD_CHECK_WRITE)
              || (mode == MZFD_CHECK_VNODE)
-             || (mode == MZFD_REMOVE)))
+             || (mode == MZFD_REMOVE)
+             || (mode == MZFD_REMOVE_VNODE)))
     return NULL;
 
   if (!v) {
@@ -3521,7 +3522,7 @@ Scheme_Object *scheme_fd_to_semaphore(intptr_t fd, int mode, int is_socket)
   e = MZ_GET_FDSET(scheme_semaphore_fd_set, 2);
 # endif
 
-  if (mode == MZFD_REMOVE) {
+  if ((mode == MZFD_REMOVE) || (mode == MZFD_REMOVE_VNODE)) {
     s = SCHEME_VEC_ELS(v)[0];
     if (!SCHEME_FALSEP(s))
       scheme_post_sema_all(s);
@@ -3532,14 +3533,24 @@ Scheme_Object *scheme_fd_to_semaphore(intptr_t fd, int mode, int is_socket)
     scheme_hash_set(scheme_semaphore_fd_mapping, key, NULL);
 # ifdef HAVE_KQUEUE_SYSCALL
     {
-      GC_CAN_IGNORE struct kevent kev[3];
+      GC_CAN_IGNORE struct kevent kev[2];
       struct timespec timeout = {0, 0};
-      int kr;
-      EV_SET(kev, fd, EVFILT_READ, EV_DELETE, 0, 0, NULL);
-      EV_SET(&kev[1], fd, EVFILT_WRITE, EV_DELETE, 0, 0, NULL);
-      EV_SET(&kev[2], fd, EVFILT_VNODE, EV_DELETE, 0, 0, NULL);
+      int kr, pos = 0;
+      if (mode == MZFD_REMOVE_VNODE) {
+        EV_SET(&kev[pos], fd, EVFILT_VNODE, EV_DELETE, 0, 0, NULL);
+        pos++;
+      } else {
+        if (SCHEME_TRUEP(SCHEME_VEC_ELS(v)[0])) {
+          EV_SET(&kev[pos], fd, EVFILT_READ, EV_DELETE, 0, 0, NULL);
+          pos++;
+        }
+        if (SCHEME_TRUEP(SCHEME_VEC_ELS(v)[1])) {
+          EV_SET(&kev[pos], fd, EVFILT_WRITE, EV_DELETE, 0, 0, NULL);
+          pos++;
+        }
+      }
       do {
-        kr = kevent(scheme_semaphore_fd_kqueue, kev, 3, NULL, 0, &timeout);
+        kr = kevent(scheme_semaphore_fd_kqueue, kev, pos, NULL, 0, &timeout);
       } while ((kr == -1) && (errno == EINTR));
       log_kqueue_error("remove", kr);
     }