diff --git a/services/hydra/default.nix b/services/hydra/default.nix
index 9240d76..685bc98 100644
--- a/services/hydra/default.nix
+++ b/services/hydra/default.nix
@@ -13,15 +13,15 @@ let
 
   # XXX: to support Nix's dumb public host key syntax (base64'd), this outputs
   # a string with shell-style command interpolations: $(...).
-  mkBaremetalBuilder = { nrCores, publicHostKey, host, speedFactor ? 1, user ? "builder", supportedSystems ? [ "i686-linux" "x86_64-linux" ], supportedFeatures ? [ "big-parallel" "kvm" "nixos-test" ] }:
-  "ssh://${user}@${host} ${lib.concatStringsSep "," supportedSystems} ${config.age.secrets.hydra-ssh-key-priv.path} ${toString nrCores} ${toString speedFactor} ${lib.concatStringsSep "," supportedFeatures} - $(echo -n '${publicHostKey}' | base64 -w0)";
+  mkBaremetalBuilder = { parallelBuilds, publicHostKey, host, speedFactor ? 1, user ? "builder", supportedSystems ? [ "i686-linux" "x86_64-linux" ], supportedFeatures ? [ "big-parallel" "kvm" "nixos-test" ] }:
+  "ssh://${user}@${host} ${lib.concatStringsSep "," supportedSystems} ${config.age.secrets.hydra-ssh-key-priv.path} ${toString parallelBuilds} ${toString speedFactor} ${lib.concatStringsSep "," supportedFeatures} - $(echo -n '${publicHostKey}' | base64 -w0)";
 
   # TODO:
   # - generalize to new architectures
   # - generalize to new features
   baremetalBuilders = lib.concatStringsSep "\n"
     (map (n: mkBaremetalBuilder {
-      nrCores = 40; # TODO: do not hardcode this, use the node's builder configuration.
+      parallelBuilds = 8; # TODO: do not hardcode this, use the node's builder configuration.
       publicHostKey = ssh-keys.machines.${n};
       host = nodes.${n}.config.networking.fqdn;
     }) cfg.builders);