diff --git a/pkgs/build-support/build-fhs-userenv/chrootenv/chrootenv.c b/pkgs/build-support/build-fhs-userenv/chrootenv/chrootenv.c
index 27e70e3fe5c4..324c9d24ba04 100644
--- a/pkgs/build-support/build-fhs-userenv/chrootenv/chrootenv.c
+++ b/pkgs/build-support/build-fhs-userenv/chrootenv/chrootenv.c
@@ -122,7 +122,7 @@ int main(gint argc, gchar **argv) {
     }
 
     // hide all mounts we do from the parent
-    fail_if(mount(0, "/", 0, MS_PRIVATE | MS_REC, 0));
+    fail_if(mount(0, "/", 0, MS_SLAVE | MS_REC, 0));
 
     if (uid != 0) {
       spit("/proc/self/setgroups", "deny");