diff --git a/upstart-jobs/halt.nix b/upstart-jobs/halt.nix
index f24904e723b..719b01258ff 100644
--- a/upstart-jobs/halt.nix
+++ b/upstart-jobs/halt.nix
@@ -47,8 +47,10 @@ script
         for mp in $(getMountPoints); do
             device=$(getDevice $mp)
             echo \"unmounting $mp...\"
-            if umount -n -r \"$mp\"; then
+            if umount -n \"$mp\"; then
                 if test \"$mp\" != /; then tryAgain=1; fi
+            else
+                mount -n -o remount,ro \"$mp\"
             fi
 
             # Hack: work around a bug in mount (mount -o remount on a