diff --git a/pkgs/tools/security/ospd-openvas/default.nix b/pkgs/tools/security/ospd-openvas/default.nix
index a77ed6ba195e..9b20f221447e 100644
--- a/pkgs/tools/security/ospd-openvas/default.nix
+++ b/pkgs/tools/security/ospd-openvas/default.nix
@@ -20,8 +20,11 @@ python3.pkgs.buildPythonApplication rec {
     "python-gnupg"
   ];
 
-  nativeBuildInputs = with python3.pkgs; [
+  build-system = with python3.pkgs; [
     poetry-core
+  ];
+
+  nativeBuildInputs = with python3.pkgs; [
     pythonRelaxDepsHook
   ];