diff --git a/synapse/metrics/background_process_metrics.py b/synapse/metrics/background_process_metrics.py

index 3a14260752..2ab599a334 100644
--- a/synapse/metrics/background_process_metrics.py
+++ b/synapse/metrics/background_process_metrics.py
@@ -265,7 +265,7 @@ class BackgroundProcessLoggingContext(LoggingContext):
         super().__init__("%s-%s" % (name, instance_id))
         self._proc = _BackgroundProcess(name, self)
 
-    def start(self, rusage: "Optional[resource._RUsage]"):
+    def start(self, rusage: "Optional[resource.struct_rusage]"):
         """Log context has started running (again)."""
 
         super().start(rusage)