diff --git a/src/cosl/grafana_dashboard.py b/src/cosl/grafana_dashboard.py
index ca41e62..aab13ac 100644
--- a/src/cosl/grafana_dashboard.py
+++ b/src/cosl/grafana_dashboard.py
@@ -8,8 +8,8 @@
 import json
 import logging
 import lzma
-from typing import Any, Dict, Union
 import warnings
+from typing import Any, Dict, Tuple, Union
 
 logger = logging.getLogger(__name__)
 
@@ -23,11 +23,17 @@ class GrafanaDashboard(str):
 
     @staticmethod
     def _serialize(raw_json: Union[str, bytes]) -> "GrafanaDashboard":
-        warnings.warn("GrafanaDashboard._serialize is deprecated; use LZMABase64.compress(json.dumps(...)) instead.", category=DeprecationWarning)
+        warnings.warn(
+            "GrafanaDashboard._serialize is deprecated; use LZMABase64.compress(json.dumps(...)) instead.",
+            category=DeprecationWarning,
+        )
         return GrafanaDashboard(LZMABase64.compress(raw_json))
 
     def _deserialize(self) -> Dict[str, Any]:
-        warnings.warn("GrafanaDashboard._deserialize is deprecated; use json.loads(LZMABase64.decompress(...)) instead.", category=DeprecationWarning)
+        warnings.warn(
+            "GrafanaDashboard._deserialize is deprecated; use json.loads(LZMABase64.decompress(...)) instead.",
+            category=DeprecationWarning,
+        )
         try:
             return json.loads(LZMABase64.decompress(self))
         except json.decoder.JSONDecodeError as e:
@@ -58,7 +64,7 @@ def decompress(cls, compressed: str) -> str:
         return lzma.decompress(base64.b64decode(compressed.encode("utf-8"))).decode()
 
 
-def _hash(components: tuple, length: int) -> str:
+def _hash(components: Tuple[str, ...], length: int) -> str:
     return hashlib.shake_256("-".join(components).encode("utf-8")).hexdigest(length)
 
 
diff --git a/tests/test_grafana_dashboard.py b/tests/test_grafana_dashboard.py
index 1f1029a..fcdfac3 100644
--- a/tests/test_grafana_dashboard.py
+++ b/tests/test_grafana_dashboard.py
@@ -31,7 +31,7 @@ class TestGenerateUID(unittest.TestCase):
     """Spec for the UID generation logic."""
 
     def test_uid_length_is_40(self):
-        self.assertEqual(40, len(generate_dashboard_uid("whatever")))
+        self.assertEqual(40, len(generate_dashboard_uid("my-charm", "my-dash.json")))
 
     def test_collisions(self):
         """A very naive and primitive collision check that is meant to catch trivial errors."""
@@ -41,6 +41,6 @@ def test_collisions(self):
         )
 
         self.assertNotEqual(
-            generate_dashboard_uid("some-charm"),
             generate_dashboard_uid("some-charm", "dashboard.json"),
+            generate_dashboard_uid("diff-charm", "dashboard.json"),
         )