diff --git a/rust/flake.nix b/rust/flake.nix
index db86b2c..060392c 100644
--- a/rust/flake.nix
+++ b/rust/flake.nix
@@ -71,6 +71,7 @@
               # rust
               rustPkgs
               rust-analyzer
+              cargo-expand # see macro expansions
 
               # nix
               nil