diff --git a/pkgs/by-name/wp/wprs/package.nix b/pkgs/by-name/wp/wprs/package.nix
index 9643140ca8d5..dd349cca0c22 100644
--- a/pkgs/by-name/wp/wprs/package.nix
+++ b/pkgs/by-name/wp/wprs/package.nix
@@ -30,7 +30,7 @@ rustPlatform.buildRustPackage {
 
   cargoHash = "sha256-krrVgdoCcW3voSiQAoWsG+rPf1HYKbuGhplhn21as2c=";
 
-  RUSTFLAGS = "-C target-feature=+avx2"; # only works on x86 systems supporting AVX2
+  env.RUSTFLAGS = "-C target-feature=+avx2"; # only works on x86 systems supporting AVX2
 
   preFixup = ''
     cp  wprs "$out/bin/wprs"