1 files changed, 9 insertions, 5 deletions
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index f237b8a236..e902109af3 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -20,7 +20,7 @@ import os
 import platform
 import threading
 import time
-from typing import Callable, Dict, Iterable, Optional, Tuple, Union
+from typing import Callable, Dict, Iterable, Mapping, Optional, Tuple, Union
 
 import attr
 from prometheus_client import Counter, Gauge, Histogram
@@ -67,7 +67,11 @@ class LaterGauge:
     labels = attr.ib(hash=False, type=Optional[Iterable[str]])
     # callback: should either return a value (if there are no labels for this metric),
     # or dict mapping from a label tuple to a value
-    caller = attr.ib(type=Callable[[], Union[Dict[Tuple[str, ...], float], float]])
+    caller = attr.ib(
+        type=Callable[
+            [], Union[Mapping[Tuple[str, ...], Union[int, float]], Union[int, float]]
+        ]
+    )
 
     def collect(self):
 
@@ -80,11 +84,11 @@ class LaterGauge:
             yield g
             return
 
-        if isinstance(calls, dict):
+        if isinstance(calls, (int, float)):
+            g.add_metric([], calls)
+        else:
             for k, v in calls.items():
                 g.add_metric(k, v)
-        else:
-            g.add_metric([], calls)
 
         yield g