diff --git a/nix/base-system/flake.nix b/nix/base-system/flake.nix
index 036179c..4a9553e 100644
--- a/nix/base-system/flake.nix
+++ b/nix/base-system/flake.nix
@@ -280,9 +280,7 @@ EOF";
         environment.systemPackages = (with pkgs; [
             # TODO(jwall): This appears to be broken due to: https://github.com/NixOS/nixpkgs/issues/166205
             # Should be fixed by: https://github.com/NixOS/nixpkgs/pull/282624
-            #isabelle
-            # Should be fixed by: https://github.com/NixOS/nixpkgs/pull/282624
-            #(lean4.override { stdenv = stdenv.override { allowedRequisites = null; cc = llvmPackages_11.clang; }; })
+            isabelle
             lean4
             terraform # TODO(jeremy): Replace with opentofu when that is an option.
             nomad