diff --git a/nixos/tests/all-tests.nix b/nixos/tests/all-tests.nix
index c577a2d7a000..51aa5ac033c5 100644
--- a/nixos/tests/all-tests.nix
+++ b/nixos/tests/all-tests.nix
@@ -1033,6 +1033,7 @@ in
     imports = [ ./ncps.nix ];
     defaults.services.ncps.cache.storage.local = "/path/to/ncps";
   };
+  ncps-storage-s3 = runTest ./ncps-storage-s3.nix;
   ndppd = runTest ./ndppd.nix;
   nebula-lighthouse-service = runTest ./nebula-lighthouse-service.nix;
   nebula.connectivity = runTest ./nebula/connectivity.nix;
diff --git a/nixos/tests/ncps-storage-s3.nix b/nixos/tests/ncps-storage-s3.nix
new file mode 100644
index 000000000000..890158dd8c4a
--- /dev/null
+++ b/nixos/tests/ncps-storage-s3.nix
@@ -0,0 +1,137 @@
+{
+  lib,
+  pkgs,
+  ...
+}:
+let
+  bucket = "ncps";
+  region = "us-west-1";
+  accessKey = "test-access-key";
+  secretKey = "test-secret-key";
+
+  initMinio = pkgs.writeShellScriptBin "init-minio.sh" ''
+    set -euo pipefail
+
+    mc alias set local "http://127.0.0.1:9000" minioadmin minioadmin
+    mc mb local/${bucket}
+    mc admin user svcacct add --access-key ${accessKey} --secret-key ${secretKey} local minioadmin
+  '';
+in
+{
+  name = "ncps-storage-s3";
+  meta = with lib.maintainers; {
+    maintainers = [ kalbasit ];
+  };
+
+  nodes = {
+    harmonia = {
+      services.harmonia = {
+        enable = true;
+        signKeyPaths = [
+          (pkgs.writeText "cache-key" "cache.example.com-1:9FhO0w+7HjZrhvmzT1VlAZw4OSAlFGTgC24Seg3tmPl4gZBdwZClzTTHr9cVzJpwsRSYLTu7hEAQe3ljy92CWg==")
+        ];
+        settings.priority = 35;
+      };
+
+      networking.firewall.allowedTCPPorts = [ 5000 ];
+      system.extraDependencies = [ pkgs.emptyFile ];
+    };
+
+    minio = {
+      services.minio = {
+        inherit region;
+
+        enable = true;
+      };
+
+      networking.firewall.allowedTCPPorts = [ 9000 ];
+      environment.systemPackages = [
+        pkgs.minio-client
+        initMinio
+      ];
+    };
+
+    ncps = {
+      services.ncps = {
+        enable = true;
+
+        cache = {
+          hostName = "ncps";
+
+          secretKeyPath = builtins.toString (
+            pkgs.writeText "ncps-cache-key" "ncps:dcrGsrku0KvltFhrR5lVIMqyloAdo0y8vYZOeIFUSLJS2IToL7dPHSSCk/fi+PJf8EorpBn8PU7MNhfvZoI8mA=="
+          );
+
+          storage.s3 = {
+            inherit bucket region;
+
+            endpoint = "http://minio:9000";
+
+            accessKeyIdPath = builtins.toFile "minio-access-key" accessKey;
+            secretAccessKeyPath = builtins.toFile "minio-secret-key" secretKey;
+          };
+
+          upstream = {
+            urls = [ "http://harmonia:5000" ];
+            publicKeys = [
+              "cache.example.com-1:eIGQXcGQpc00x6/XFcyacLEUmC07u4RAEHt5Y8vdglo="
+            ];
+          };
+        };
+      };
+
+      networking.firewall.allowedTCPPorts = [ 8501 ];
+    };
+
+    client = {
+      nix.settings = {
+        substituters = lib.mkForce [ "http://ncps:8501" ];
+        trusted-public-keys = lib.mkForce [
+          "ncps:UtiE6C+3Tx0kgpP34vjyX/BKK6QZ/D1OzDYX72aCPJg="
+        ];
+      };
+    };
+  };
+
+  testScript =
+    { nodes, ... }:
+    let
+      narinfoName =
+        (lib.strings.removePrefix "/nix/store/" (
+          lib.strings.removeSuffix "-empty-file" pkgs.emptyFile.outPath
+        ))
+        + ".narinfo";
+
+      narinfoNameChars = lib.strings.stringToCharacters narinfoName;
+
+      narinfoPath = lib.concatStringsSep "/" [
+        (builtins.head nodes.minio.services.minio.dataDir)
+        bucket
+        "store/narinfo"
+        (lib.lists.elemAt narinfoNameChars 0)
+        ((lib.lists.elemAt narinfoNameChars 0) + (lib.lists.elemAt narinfoNameChars 1))
+        narinfoName
+        "xl.meta"
+      ];
+    in
+    ''
+      minio.start()
+
+      minio.wait_for_unit("minio.service")
+
+      minio.wait_until_succeeds("init-minio.sh")
+
+      start_all()
+
+      harmonia.wait_for_unit("harmonia.service")
+
+      ncps.wait_for_unit("ncps.service")
+
+      client.wait_until_succeeds("curl -f http://ncps:8501/ | grep '\"hostname\":\"${toString nodes.ncps.services.ncps.cache.hostName}\"' >&2")
+
+      client.succeed("cat /etc/nix/nix.conf >&2")
+      client.succeed("nix-store --realise ${pkgs.emptyFile}")
+
+      minio.succeed("cat ${narinfoPath} >&2")
+    '';
+}