diff --git a/global/gui/default.nix b/global/gui/default.nix
index 5c573d35..3b2082de 100644
--- a/global/gui/default.nix
+++ b/global/gui/default.nix
@@ -17,7 +17,7 @@ in {
     enable = mkEnableOption "various setup required for GUI and support software";
     session = mkEnableOption "software required for a graphical session" // { default = true; };
     type = mkOption {
-      type = with types; nullOr enum [ "intel" "amdgpu" "nvidia" "prime" ];
+      type = with types; nullOr (enum [ "intel" "amdgpu" "nvidia" "prime" ]);
       default = null;
       description = "type of graphics acceleration used";
     };