diff --git a/lisp/generic-x.el b/lisp/generic-x.el
index b4ae0225943..373bfad92dd 100644
--- a/lisp/generic-x.el
+++ b/lisp/generic-x.el
@@ -1491,6 +1491,7 @@ etc-fstab-generic-mode
     "cd9660"
     "cfs"
     "cgroup"
+    "cgroup2"
     "cifs"
     "coda"
     "coherent"