diff --git a/flake.nix b/flake.nix
index 03dcad0..ba8b1f9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,12 +1,16 @@
 {
   description = "Not-OS port to the Zynq-7000 platform";
   
-  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
+  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-23.05;
+  inputs.nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
   inputs.not-os.url = github:cleverca22/not-os;
+  inputs.not-os.inputs.nixpkgs.follows = "nixpkgs";
   
-  outputs = { self, nixpkgs, not-os }:
+  outputs = { self, nixpkgs, nixpkgs-unstable, not-os }:
     let
       pkgs = import nixpkgs { system = "x86_64-linux"; };
+      # To be used for building u-boot.
+      pkgs-unstable = import nixpkgs-unstable { system = "x86_64-linux"; };
 
       gnu-platform = "arm-none-eabi";
 
@@ -174,7 +178,9 @@
         dontFixup = true;
       };
 
-      u-boot = pkgs.pkgsCross.armv7l-hf-multiplatform.buildUBoot {   
+      # U-boot needs the recent patch in master to fix cross-compile issues.
+      # See https://github.com/NixOS/nixpkgs/pull/265411.
+      u-boot = pkgs-unstable.pkgsCross.armv7l-hf-multiplatform.buildUBoot {
         defconfig = "xilinx_zynq_virt_defconfig";
         preConfigure = ''
           export DEVICE_TREE=zynq-zc706