diff --git a/pkgs/development/tools/rust/bindgen/unwrapped.nix b/pkgs/development/tools/rust/bindgen/unwrapped.nix
index cf1624fec9a0..af24dcb64838 100644
--- a/pkgs/development/tools/rust/bindgen/unwrapped.nix
+++ b/pkgs/development/tools/rust/bindgen/unwrapped.nix
@@ -34,7 +34,7 @@ rustPlatform.buildRustPackage rec {
   doCheck = true;
   nativeCheckInputs = [ clang ];
 
-  RUSTFMT = "${rustfmt-nightly}/bin/rustfmt";
+  env.RUSTFMT = "${rustfmt-nightly}/bin/rustfmt";
 
   preCheck = ''
     # for the ci folder, notably