diff --git a/src/labthings_fastapi/actions.py b/src/labthings_fastapi/actions.py
index 18f6acf..95b9910 100644
--- a/src/labthings_fastapi/actions.py
+++ b/src/labthings_fastapi/actions.py
@@ -41,7 +41,7 @@
 
 from .base_descriptor import BaseDescriptor
 from .logs import add_thing_log_destination
-from .utilities import model_to_dict
+from .utilities import model_to_dict, wrap_plain_types_in_rootmodel
 from .invocations import InvocationModel, InvocationStatus, LogRecordModel
 from .dependencies.invocation import NonWarningInvocationID
 from .exceptions import (
@@ -477,7 +477,6 @@ def list_all_invocations(
 
         @app.get(
             ACTION_INVOCATIONS_PATH + "/{id}",
-            response_model=InvocationModel,
             responses={404: {"description": "Invocation ID not found"}},
         )
         def action_invocation(
@@ -683,7 +682,7 @@ def __init__(
             remove_first_positional_arg=True,
             ignore=[p.name for p in self.dependency_params],
         )
-        self.output_model = return_type(func)
+        self.output_model = wrap_plain_types_in_rootmodel(return_type(func))
         self.invocation_model = create_model(
             f"{name}_invocation",
             __base__=InvocationModel,
diff --git a/tests/test_actions.py b/tests/test_actions.py
index 6994701..d08c6e6 100644
--- a/tests/test_actions.py
+++ b/tests/test_actions.py
@@ -161,7 +161,7 @@ def action_wrapper(*args, **kwargs):
     return action_wrapper
 
 
-def assert_input_models_equivalent(model_a, model_b):
+def assert_models_equivalent(model_a, model_b):
     """Check two basemodels are equivalent."""
     keys = list(model_a.model_fields.keys())
     assert list(model_b.model_fields.keys()) == keys
@@ -198,11 +198,10 @@ def decorated(
             """An example decorated action with type annotations."""
             return 0.5
 
-    assert_input_models_equivalent(
-        Example.action.input_model, Example.decorated.input_model
+    assert_models_equivalent(Example.action.input_model, Example.decorated.input_model)
+    assert_models_equivalent(
+        Example.action.output_model, Example.decorated.output_model
     )
-    assert Example.action.output_model == Example.decorated.output_model
-
     # Check we can make the thing and it has a valid TD
     example = create_thing_without_server(Example)
     example.validate_thing_description()
diff --git a/tests/test_numpy_type.py b/tests/test_numpy_type.py
index 1f53f6c..cf1d5c9 100644
--- a/tests/test_numpy_type.py
+++ b/tests/test_numpy_type.py
@@ -2,6 +2,7 @@
 
 from pydantic import BaseModel, RootModel
 import numpy as np
+from fastapi.testclient import TestClient
 
 from labthings_fastapi.testing import create_thing_without_server
 from labthings_fastapi.types.numpy import NDArray, DenumpifyingDict
@@ -70,6 +71,14 @@ class MyNumpyThing(lt.Thing):
     def action_with_arrays(self, a: NDArray) -> NDArray:
         return a * 2
 
+    @lt.action
+    def read_array(self) -> NDArray:
+        return np.array([1, 2])
+
+    @lt.property
+    def array_property(self) -> NDArray:
+        return np.array([3, 4, 5])
+
 
 def test_thing_description():
     """Make sure the TD validates when numpy types are used."""
@@ -102,3 +111,16 @@ def test_rootmodel():
         m = ArrayModel(root=input)
         assert isinstance(m.root, np.ndarray)
         assert (m.model_dump() == [0, 1, 2]).all()
+
+
+def test_numpy_over_http():
+    """Read numpy array over http."""
+    server = lt.ThingServer({"np_thing": MyNumpyThing})
+    with TestClient(server.app) as client:
+        np_thing_client = lt.ThingClient.from_url("/np_thing/", client=client)
+
+        arrayprop = np_thing_client.array_property
+        assert np.array_equal(np.asarray(arrayprop), np.array([3, 4, 5]))
+
+        array = np_thing_client.read_array()
+        assert np.array_equal(np.asarray(array), np.array([1, 2]))