diff --git a/flake.nix b/flake.nix
index 95ac7b6..a4f2cd6 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,5 +1,6 @@
 {
   inputs = {
+    nixpkgs.url = "nixpkgs/nixos-21.11";
     flake-utils.url = "github:numtide/flake-utils";
   };