diff --git a/deploy/nixos/hardware/raspberry-pi-5.nix b/deploy/nixos/hardware/raspberry-pi-5.nix
index 6e56ff1..f0f4558 100644
--- a/deploy/nixos/hardware/raspberry-pi-5.nix
+++ b/deploy/nixos/hardware/raspberry-pi-5.nix
@@ -30,7 +30,12 @@
   # Primary UART (GPIO 14/15) available for a GPIO-wired validator. Keep the
   # serial console OFF it so the validator owns the line — mirrors upboard.nix
   # keeping ttyS4 free for the dispenser. USB-serial adapters are unaffected.
-  boot.kernelParams = lib.mkDefault [ "console=tty0" ];
+  #
+  # Not mkDefault: kernelParams is list-merged, and only definitions at the
+  # highest priority survive. nixpkgs sets loglevel/lsm at normal priority, so
+  # a mkDefault list here is dropped entirely — and with no console= at all
+  # the kernel falls back to the device tree's stdout-path, i.e. this UART.
+  boot.kernelParams = [ "console=tty0" ];
 
   # X uses the Pi GPU's kernel modesetting driver (vc4/v3d KMS from
   # nixos-hardware). Electron renders through it as on the UP Board.