diff --git a/src/openflexure_microscope_server/things/camera/__init__.py b/src/openflexure_microscope_server/things/camera/__init__.py
index f05c19fa..a76914d6 100644
--- a/src/openflexure_microscope_server/things/camera/__init__.py
+++ b/src/openflexure_microscope_server/things/camera/__init__.py
@@ -491,7 +491,7 @@ class BaseCamera(lt.Thing):
     def _capture_metadata(
         self,
         metadata: dict,
-    ) -> None:
+    ) -> dict:
         """Return the metadata for a capture, from the thing states, time and known names."""
         return {
             "capture_time": datetime.now().timestamp(),