diff --git a/radxa/rock-4c-plus/default.nix b/radxa/rock-4c-plus/default.nix
index 7550483..e432dd7 100644
--- a/radxa/rock-4c-plus/default.nix
+++ b/radxa/rock-4c-plus/default.nix
@@ -13,7 +13,7 @@
       radxa.enable = true;
       rockchip = {
         rk3399.enable = true;
-        platformFirmware = pkgs.ubootRock4CPlus;
+        platformFirmware = lib.mkDefault pkgs.ubootRock4CPlus;
       };
     };
   };
diff --git a/radxa/rock-5b/default.nix b/radxa/rock-5b/default.nix
index aff9a81..c8a899d 100644
--- a/radxa/rock-5b/default.nix
+++ b/radxa/rock-5b/default.nix
@@ -13,7 +13,7 @@
       radxa.enable = true;
       rockchip = {
         rk3588.enable = true;
-        platformFirmware = pkgs.ubootRock5ModelB;
+        platformFirmware = lib.mkDefault pkgs.ubootRock5ModelB;
       };
     };
   };
diff --git a/radxa/rock-pi-4/default.nix b/radxa/rock-pi-4/default.nix
index 74b97dd..e205a46 100644
--- a/radxa/rock-pi-4/default.nix
+++ b/radxa/rock-pi-4/default.nix
@@ -13,7 +13,7 @@
       radxa.enable = true;
       rockchip = {
         rk3399.enable = true;
-        platformFirmware = pkgs.ubootRockPi4;
+        platformFirmware = lib.mkDefault pkgs.ubootRockPi4;
       };
     };
   };
diff --git a/radxa/rock-pi-e/default.nix b/radxa/rock-pi-e/default.nix
index 4328ca7..0eec4e9 100644
--- a/radxa/rock-pi-e/default.nix
+++ b/radxa/rock-pi-e/default.nix
@@ -13,7 +13,7 @@
       radxa.enable = true;
       rockchip = {
         rk3328.enable = true;
-        platformFirmware = pkgs.ubootRockPiE;
+        platformFirmware = lib.mkDefault pkgs.ubootRockPiE;
       };
     };
   };