diff --git a/nix/update-crates.sh b/nix/update-crates.sh
index 7e5ace5..17e8152 100755
--- a/nix/update-crates.sh
+++ b/nix/update-crates.sh
@@ -2,5 +2,5 @@
 #!nix-shell -i bash -E "with import <nixpkgs> {}; mkShell { nativeBuildInputs = [ (import (builtins.fetchTarball https://github.com/kolloch/crate2nix/archive/0.8.0.tar.gz) {}) ]; }"
 set -e
 
-cargo build
+cargo fetch --locked
 crate2nix generate