Index: lib/libc/sys/read.2
===================================================================
--- lib/libc/sys/read.2
+++ lib/libc/sys/read.2
@@ -28,7 +28,7 @@
 .\"     @(#)read.2	8.4 (Berkeley) 2/26/94
 .\" $FreeBSD$
 .\"
-.Dd March 30, 2020
+.Dd May 13, 2020
 .Dt READ 2
 .Os
 .Sh NAME
@@ -199,9 +199,10 @@
 The file was marked for non-blocking I/O,
 and no data were ready to be read.
 .It Bq Er EISDIR
-The file descriptor is associated with a directory residing
-on a file system that does not allow regular read operations on
-directories (e.g.\& NFS).
+The file descriptor is associated with a directory.
+The
+.Xr readdir 3
+function should be used instead.
 .It Bq Er EOPNOTSUPP
 The file descriptor is associated with a file system and file type that
 do not allow regular read operations on it.
Index: sys/kern/vfs_vnops.c
===================================================================
--- sys/kern/vfs_vnops.c
+++ sys/kern/vfs_vnops.c
@@ -792,6 +792,8 @@
 	    uio->uio_td, td));
 	KASSERT(flags & FOF_OFFSET, ("No FOF_OFFSET"));
 	vp = fp->f_vnode;
+	if (vp->v_type == VDIR)
+		return (EISDIR);
 	ioflag = 0;
 	if (fp->f_flag & FNONBLOCK)
 		ioflag |= IO_NDELAY;