--- a/sys/kern/vfs_nlookup.c
+++ b/sys/kern/vfs_nlookup.c
@@ -647,11 +647,18 @@
 	 * Optimize by passing-in NULL for any prior components, which may
 	 * allow the code to bypass the naccess() call.
 	 *
+	 * NOTE: Whether the current component is the last one must be
+	 * determined with islastelement(), which skips trailing slashes.
+	 * Testing *nptr != '/' misclassifies the parent directory of a leaf
+	 * followed by a trailing '/' as an intermediate directory and drops
+	 * the NLC_STICKY / NLC_APPENDONLY feedback flags, bypassing the
+	 * sticky-bit and append-only directory deletion restrictions.
+	 *
 	 * naccess() is optimized to avoid having to lock the nch or get
 	 * the related vnode if cached perms are sufficient.
 	 */
 	dflags = 0;
-	if (*nptr == '/' || (saveflag & NLC_MODIFYING_MASK) == 0) {
+	if (islastelement(nptr) == 0 || (saveflag & NLC_MODIFYING_MASK) == 0) {
 	    error = naccess(nd, &nd->nl_nch, &nl_gen, NLC_EXEC,
 			    nd->nl_cred, NULL, 0);
 	} else {