diff --git a/flake.nix b/flake.nix
index 1822811..654f405 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,7 +5,7 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
     nixpkgs = {
-      url = "github:nixos/nixpkgs/nixos-unstable";
+      url = "github:nixos/nixpkgs/nixos-21.11";
     };
     flake-utils = {
       url = "github:numtide/flake-utils";