diff --git a/nixos/tests/vault.nix b/nixos/tests/vault.nix
index ac8cf0703da5..20cc8f4c6922 100644
--- a/nixos/tests/vault.nix
+++ b/nixos/tests/vault.nix
@@ -8,6 +8,7 @@ import ./make-test-python.nix ({ pkgs, ... }:
     environment.systemPackages = [ pkgs.vault ];
     environment.variables.VAULT_ADDR = "http://127.0.0.1:8200";
     services.vault.enable = true;
+    virtualisation.memorySize = 512;
   };
 
   testScript =