diff --git a/public/service-hydra-core.nix b/public/service-hydra-core.nix
index fafaa7a..1d84b6f 100644
--- a/public/service-hydra-core.nix
+++ b/public/service-hydra-core.nix
@@ -17,6 +17,8 @@ let
     sha256 = "0nimqsbpjxfwha6d5gp6a7jh50i83z1llmx30da4bscsic8z1xly";
   };
 
+  hydra-src-pkg = lib.mkDefault ((import (hydra-src + /release.nix) {}).build.x86_64-linux);
+
   # information pour l'état de hydra :
   # hydra-queue-runner --status | json_pp
 in
@@ -56,7 +58,11 @@ mkIf cfg.hydra-core {
     listenHost = "localhost";
     minimumDiskFree = 50; # Go
     smtpHost = "localhost";
-    package = lib.mkDefault ((import (hydra-src + /release.nix) {}).build.x86_64-linux);
+    package = hydra-src-pkg ;
+  };
+
+  systemd.services.hydra-evaluator = {
+    path = [ pkgs.nettools config.services.hydra.package ];
   };
 
   ## Ménage