diff --git a/flake.nix b/flake.nix
index 85969509..50a60f85 100644
--- a/flake.nix
+++ b/flake.nix
@@ -8,7 +8,7 @@
   outputs = { self, nixpkgs, nix }:
     let
 
-      version = "${builtins.readFile ./version}.${builtins.substring 0 8 self.lastModified}.${self.shortRev or "DIRTY"}";
+      version = "${builtins.readFile ./version}.${builtins.substring 0 8 self.lastModifiedDate}.${self.shortRev or "DIRTY"}";
 
       pkgs = import nixpkgs {
         system = "x86_64-linux";