diff --git a/daemon/grub.c b/daemon/grub.c
index d0eab19fc..6b454afd0 100644
--- a/daemon/grub.c
+++ b/daemon/grub.c
@@ -38,7 +38,7 @@ do_grub_install (const char *root, const char *device)
   int r;
   CLEANUP_FREE char *err = NULL, *buf = NULL, *out = NULL;
 
-  if (asprintf_nowarn (&buf, "--root-directory=%R", root) == -1) {
+  if (asprintf (&buf, "--root-directory=%s%s", sysroot, root) == -1) {
     reply_with_perror ("asprintf");
     return -1;
   }