diff --git a/pkgs/by-name/ha/hal-hardware-analyzer/package.nix b/pkgs/by-name/ha/hal-hardware-analyzer/package.nix
index c61f8c3d8500..89bdf10118a6 100644
--- a/pkgs/by-name/ha/hal-hardware-analyzer/package.nix
+++ b/pkgs/by-name/ha/hal-hardware-analyzer/package.nix
@@ -87,7 +87,9 @@ stdenv.mkDerivation (finalAttrs: {
   cmakeBuildType = "MinSizeRel";
 
   # https://github.com/emsec/hal/issues/598
-  NIX_CFLAGS_COMPILE = lib.optional stdenv.hostPlatform.isAarch64 "-flax-vector-conversions";
+  env = lib.optionalAttrs stdenv.hostPlatform.isAarch64 {
+    NIX_CFLAGS_COMPILE = "-flax-vector-conversions";
+  };
 
   # some plugins depend on other plugins and need to be able to load them
   postFixup = lib.optionalString stdenv.hostPlatform.isLinux ''