diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index f04aadfa4c8..50e05c239d9 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -88,4 +88,4 @@ repos:
           - zict
           - pyarrow
 
-# Increase this by 1 to force-wipe the pre-commit github action cache: 1
+# Increase this by 1 to force-wipe the pre-commit github action cache: 2
diff --git a/distributed/system_monitor.py b/distributed/system_monitor.py
index 80c2e1c1d54..d92dac6c119 100644
--- a/distributed/system_monitor.py
+++ b/distributed/system_monitor.py
@@ -70,8 +70,7 @@ def __init__(
             else:
                 if disk_ioc is None:  # pragma: nocover
                     # diskless machine
-                    # FIXME https://github.com/python/typeshed/pull/8829
-                    monitor_disk_io = False  # type: ignore[unreachable]
+                    monitor_disk_io = False
                 else:
                     self._last_disk_io_counters = disk_ioc
                     self.quantities["host_disk_io.read_bps"] = deque(maxlen=maxlen)
@@ -143,6 +142,7 @@ def update(self) -> dict[str, Any]:
 
         if self.monitor_disk_io:
             disk_ioc = psutil.disk_io_counters()
+            assert disk_ioc is not None
             last_disk = self._last_disk_io_counters
             result["host_disk_io.read_bps"] = (
                 disk_ioc.read_bytes - last_disk.read_bytes