diff --git a/modules/services/x11/display-managers/kdm.nix b/modules/services/x11/display-managers/kdm.nix
index e0a85f66f07..5264aa78228 100644
--- a/modules/services/x11/display-managers/kdm.nix
+++ b/modules/services/x11/display-managers/kdm.nix
@@ -14,7 +14,7 @@ let
       [Shutdown]
       HaltCmd=${pkgs.upstart}/sbin/halt
       RebootCmd=${pkgs.upstart}/sbin/reboot
-      ${optionalString (config.boot.grubDevice != "") ''
+      ${optionalString (config.system.boot.loader.id == "grub") ''
         BootManager=Grub
       ''}