diff --git a/nixos/modules/services/x11/display-managers/lightdm.nix b/nixos/modules/services/x11/display-managers/lightdm.nix
index 8226f2cf0be5..be0f4bf368bb 100644
--- a/nixos/modules/services/x11/display-managers/lightdm.nix
+++ b/nixos/modules/services/x11/display-managers/lightdm.nix
@@ -156,7 +156,7 @@ in
       };
 
       background = mkOption {
-        type = types.either types.path (types.strMatching "^#[0-9]{6}$");
+        type = types.either types.path (types.strMatching "^#[0-9A-Fa-f]{6}$");
         # Manual cannot depend on packages, we are actually setting the default in config below.
         defaultText = literalExpression "pkgs.nixos-artwork.wallpapers.simple-dark-gray-bottom.gnomeFilePath";
         description = ''