diff --git a/pkgs/development/tools/knightos/regenkfs/default.nix b/pkgs/development/tools/knightos/regenkfs/default.nix
index 8b80368cdaa..c50b10527f5 100644
--- a/pkgs/development/tools/knightos/regenkfs/default.nix
+++ b/pkgs/development/tools/knightos/regenkfs/default.nix
@@ -12,7 +12,8 @@ rustPlatform.buildRustPackage {
   };
 
   cargoSha256 = "sha256-05VmQdop4vdzw2XEvVdp9+RNmyZvay1Q7gKN2n8rDEQ=";
-  cargoBuildFlags = [ "--features=c-undef" ];
+
+  buildFeatures = [ "c-undef" ];
 
   meta = with lib; {
     description = "Reimplementation of genkfs in Rust";