diff --git a/default.nix b/default.nix
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--- /dev/null
+++ b/default.nix
@@ -0,0 +1,3 @@
+# This is a nix-shell configuration to load nodejs in an impure shell, which
+# is required by Spotless to format XML code.
+with import <nixpkgs> { }; mkShell { buildInputs = [ nodejs-16_x ]; }