diff --git a/tests/test_reparameterisations/test_reparam_dict.py b/tests/test_reparameterisations/test_reparam_dict.py
new file mode 100644
index 00000000..e1b50d67
--- /dev/null
+++ b/tests/test_reparameterisations/test_reparam_dict.py
@@ -0,0 +1,64 @@
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from nessai.reparameterisations import (
+    KnownReparameterisation,
+    ReparameterisationDict,
+)
+
+
+def test_known_reparameterisation():
+    known = KnownReparameterisation("test", "class", {"key": "value"})
+    assert known.name == "test"
+    assert known.class_fn == "class"
+    assert known.keyword_arguments == {"key": "value"}
+
+
+def test_known_reparameterisation_no_kwargs():
+    known = KnownReparameterisation("test", "class")
+    assert known.name == "test"
+    assert known.class_fn == "class"
+    assert known.keyword_arguments == {}
+
+
+def test_reparameterisation_dict_add_reparam():
+    reparam_dict = ReparameterisationDict()
+    reparam_dict.add_reparameterisation("test", "class", {"key": "value"})
+    assert reparam_dict["test"].name == "test"
+    assert reparam_dict["test"].class_fn == "class"
+    assert reparam_dict["test"].keyword_arguments == {"key": "value"}
+
+
+def test_reparameterisation_dict_add_reparam_existing_entry():
+    reparam_dict = ReparameterisationDict(
+        {"test": KnownReparameterisation("test", "class", {"key": "value"})}
+    )
+    with pytest.raises(
+        ValueError, match="Reparameterisation test already exists"
+    ):
+        reparam_dict.add_reparameterisation("test", "class", {"key": "value"})
+
+
+def test_reparameterisation_dict_add_external_reparam():
+    reparam_dict = ReparameterisationDict()
+    # Mock class
+    external_reparam = KnownReparameterisation(
+        "external_reparam", "class", {"key": "value"}
+    )
+
+    # Mock what is normally returned by the entry point before they are loaded
+    EntryPointClass = MagicMock(spec=["load"])
+    EntryPointClass.load = MagicMock(return_value=external_reparam)
+
+    # Always return the version that needs to be loaded
+    with patch(
+        "nessai.reparameterisations.get_entry_points",
+        return_value={"external_class": EntryPointClass},
+    ) as mock_get_entry_points:
+        reparam_dict.add_external_reparameterisations(
+            "nessai.reparameterisations"
+        )
+    mock_get_entry_points.assert_called_once_with("nessai.reparameterisations")
+
+    assert external_reparam == reparam_dict["external_reparam"]