diff --git a/nixos/modules/services/x11/desktop-managers/xterm.nix b/nixos/modules/services/x11/desktop-managers/xterm.nix
index 29752ff405e..6ff1ef0e4c9 100644
--- a/nixos/modules/services/x11/desktop-managers/xterm.nix
+++ b/nixos/modules/services/x11/desktop-managers/xterm.nix
@@ -12,6 +12,7 @@ in
   options = {
 
     services.xserver.desktopManager.xterm.enable = mkOption {
+      type = types.bool;
       default = true;
       description = "Enable a xterm terminal as a desktop manager.";
     };