diff --git a/nixos/tests/prometheus.nix b/nixos/tests/prometheus.nix
index 6881c659e6d0..70ac78a4a468 100644
--- a/nixos/tests/prometheus.nix
+++ b/nixos/tests/prometheus.nix
@@ -36,6 +36,7 @@ in import ./make-test-python.nix {
   nodes = {
     prometheus = { pkgs, ... }: {
       virtualisation.diskSize = 2 * 1024;
+      virtualisation.memorySize = 2048;
       environment.systemPackages = [ pkgs.jq ];
       networking.firewall.allowedTCPPorts = [ grpcPort ];
       services.prometheus = {
@@ -132,6 +133,7 @@ in import ./make-test-python.nix {
 
     store = { pkgs, ... }: {
       virtualisation.diskSize = 2 * 1024;
+      virtualisation.memorySize = 2048;
       environment.systemPackages = with pkgs; [ jq thanos ];
       services.thanos.store = {
         enable = true;