diff --git a/flake.nix b/flake.nix
index b5a7705..fd704ac 100644
--- a/flake.nix
+++ b/flake.nix
@@ -28,7 +28,9 @@
           default = import ./shell.nix {
             inherit pkgs;
             additionalBuildInputs = [
-              (pkgs.rust-bin.selectLatestNightlyWith (toolchain: toolchain.default))
+              (pkgs.rust-bin.selectLatestNightlyWith (toolchain: toolchain.default.override {
+                extensions = [ "rust-src" ];
+              }))
             ];
           };
         });