diff --git a/pkgs/clan-cli/clan_cli/tests/fixtures_flakes.py b/pkgs/clan-cli/clan_cli/tests/fixtures_flakes.py
index f32566b74..76cae2d0b 100644
--- a/pkgs/clan-cli/clan_cli/tests/fixtures_flakes.py
+++ b/pkgs/clan-cli/clan_cli/tests/fixtures_flakes.py
@@ -39,6 +39,7 @@ def substitute(
     file: Path,
     clan_core_flake: Path | None = None,
     flake: Path = Path(__file__).parent,
+    inventory_expr: str = r"{}",
 ) -> None:
     sops_key = str(flake.joinpath("sops.key"))
     buf = ""
@@ -54,6 +55,7 @@ def substitute(
                     "https://git.clan.lol/clan/clan-core/archive/main.tar.gz",
                     f"path:{clan_core_flake}",
                 )
+                line = line.replace("__INVENTORY_EXPR__", str(inventory_expr))
             line = line.replace("__CLAN_SOPS_KEY_PATH__", sops_key)
             line = line.replace("__CLAN_SOPS_KEY_DIR__", str(flake / "facts"))
             buf += line
@@ -252,6 +254,7 @@ def create_flake(
     machines: list[str] | None = None,
     # alternatively specify the machines directly including their config
     machine_configs: dict[str, dict] | None = None,
+    inventory_expr: str = r"{}",
 ) -> Iterator[FlakeForTest]:
     """
     Creates a flake with the given name and machines.
@@ -279,7 +282,11 @@ def create_flake(
     for machine_name in machines:
         machine_path = Path(__file__).parent / "machines" / machine_name
         shutil.copytree(machine_path, flake / "machines" / machine_name)
-        substitute(flake / "machines" / machine_name / "default.nix", flake)
+        substitute(
+            flake / "machines" / machine_name / "default.nix",
+            flake,
+            inventory_expr=inventory_expr,
+        )
 
     # generate machines from machineConfigs
     for machine_name, machine_config in machine_configs.items():
@@ -291,7 +298,7 @@ def create_flake(
     # provided by get_test_flake_toplevel
     flake_nix = flake / "flake.nix"
     # this is where we would install the sops key to, when updating
-    substitute(flake_nix, clan_core_flake, flake)
+    substitute(flake_nix, clan_core_flake, flake, inventory_expr=inventory_expr)
     nix_options = []
     if tmp_store := nix_test_store():
         nix_options += ["--store", str(tmp_store)]
@@ -345,8 +352,12 @@ def test_flake(
 
 @pytest.fixture
 def test_flake_with_core(
-    monkeypatch: pytest.MonkeyPatch, temporary_home: Path
+    request: pytest.FixtureRequest,
+    monkeypatch: pytest.MonkeyPatch,
+    temporary_home: Path,
 ) -> Iterator[FlakeForTest]:
+    test_params = getattr(request, "param", {})  # Default if not parametrized
+    inventory_expr = test_params.get("inventory_expr", r"{}")  # Default empty inventory
     if not (CLAN_CORE / "flake.nix").exists():
         msg = "clan-core flake not found. This test requires the clan-core flake to be present"
         raise FixtureError(msg)
@@ -355,4 +366,5 @@ def test_flake_with_core(
         flake_template="test_flake_with_core",
         clan_core_flake=CLAN_CORE,
         monkeypatch=monkeypatch,
+        inventory_expr=inventory_expr,
     )
diff --git a/pkgs/clan-cli/clan_cli/tests/test_flake_with_core/flake.nix b/pkgs/clan-cli/clan_cli/tests/test_flake_with_core/flake.nix
index 7998e5818..35a11821a 100644
--- a/pkgs/clan-cli/clan_cli/tests/test_flake_with_core/flake.nix
+++ b/pkgs/clan-cli/clan_cli/tests/test_flake_with_core/flake.nix
@@ -22,6 +22,9 @@
       clan = clan-core.clanLib.buildClan {
         inherit self;
         meta.name = "test_flake_with_core";
+        # Don't quote this will be replaced by the inventory expression
+        # Not a string!
+        inventory = __INVENTORY_EXPR__;
         machines = {
           vm1 =
             { config, ... }:
diff --git a/pkgs/clan-cli/clan_cli/tests/test_inventory_serde.py b/pkgs/clan-cli/clan_cli/tests/test_inventory_serde.py
new file mode 100644
index 000000000..cec2b6912
--- /dev/null
+++ b/pkgs/clan-cli/clan_cli/tests/test_inventory_serde.py
@@ -0,0 +1,56 @@
+from typing import Any
+
+import pytest
+
+# Functions to test
+from clan_cli.inventory import load_inventory_eval
+from clan_cli.tests.fixtures_flakes import FlakeForTest
+
+
+@pytest.mark.parametrize(
+    "test_flake_with_core",
+    [
+        # Emtpy inventory
+        {"inventory_expr": r"{ }"},
+        # Empty machines
+        {
+            "inventory_expr": r"""{
+                machines.jon = {};
+                machines.sara = {};
+            }"""
+        },
+        # TODO: Test
+        # - Function modules
+        # - Instances with non-deserializable settings ?
+        # - Tags function modules
+        # -
+        # {
+        #     "inventory_expr": r"""{
+        #         modules.messager = { ... }: { };
+        #     }"""
+        # },
+    ],
+    # Important!
+    # tells pytest to pass these values to the fixture
+    # So we can write it to the flake fixtures
+    indirect=True,
+)
+@pytest.mark.with_core
+def test_inventory_deserialize_variants(
+    test_flake_with_core: FlakeForTest,
+) -> None:
+    """
+    Testing different inventory deserializations
+    Inventory should always be deserializable to a dict
+    """
+    inventory: dict[str, Any] = load_inventory_eval(test_flake_with_core.path)  # type: ignore
+    # Check that the inventory is a dict
+    assert isinstance(inventory, dict)
+
+    # Check that all keys are present
+    assert "meta" in inventory
+    assert "machines" in inventory
+    assert "services" in inventory
+    assert "tags" in inventory
+    assert "modules" in inventory
+    assert "instances" in inventory