diff --git a/tests/lib/config.nix b/tests/lib/config.nix
index fe66875..6708f50 100644
--- a/tests/lib/config.nix
+++ b/tests/lib/config.nix
@@ -1,4 +1,12 @@
+{
+  lib,
+  ...
+}:
+
 {
   # Testing eval failures that result from stateVersion assertion is out of scope
   mailserver.stateVersion = 999;
+
+  # Enable second CPU core
+  virtualisation.cores = lib.mkDefault 2;
 }