diff --git a/src/image_builder.rs b/src/image_builder.rs
index e2dd2ac..4a6b047 100644
--- a/src/image_builder.rs
+++ b/src/image_builder.rs
@@ -25,10 +25,10 @@ use tempfile::tempdir;
 use crate::nixos;
 use crate::shell::*;
 
-const NIX_VERSION: &str = "2.25.2";
+const NIX_VERSION: &str = "2.24.12";
 
 const NIX_CONF: &str = "experimental-features = nix-command flakes
-extra-nix-path = nixpkgs=flake:nixpkgs
+extra-nix-path = nixpkgs=github:nixos/nixpkgs/nixos-24.11
 build-users-group =
 sandbox = false
 ";
diff --git a/src/nixos.rs b/src/nixos.rs
index 8a96d86..e1a487e 100644
--- a/src/nixos.rs
+++ b/src/nixos.rs
@@ -8,6 +8,8 @@ use std::{
 use anyhow::{bail, Context, Result};
 use regex::Regex;
 
+const NIXOS_VERSION: &str = "24.11";
+
 pub(crate) const ENV_VARS: [(&str, &str); 4] = [
     ("PATH", "/nix/.bin"),
     ("NIX_CONF_DIR", "/nix/etc"),
@@ -76,6 +78,7 @@ pub fn build_flake_from_package_list(
         match &caps[1] {
             "name" => name,
             "description" => description,
+            "version" => NIXOS_VERSION,
             "packages" => &package_list,
             _ => "",
         }
diff --git a/src/templates/flake.nix b/src/templates/flake.nix
index a056bf8..5511fc7 100644
--- a/src/templates/flake.nix
+++ b/src/templates/flake.nix
@@ -1,7 +1,7 @@
 {
   description = "{{ description }}";
   inputs = {
-    nixpkgs.url = "flake:nixpkgs";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-{{ version }}";
     flake-utils.url = "github:numtide/flake-utils";
   };