diff --git a/subiquity/controllers/filesystem.py b/subiquity/controllers/filesystem.py
index 28c663c6f..e264a2e0d 100644
--- a/subiquity/controllers/filesystem.py
+++ b/subiquity/controllers/filesystem.py
@@ -123,7 +123,7 @@ def _check_probe_timeout(self):
     def _reprobe(self):
         self._probe_state = ProbeState.REPROBING
         self.run_in_bg(
-            lambda: self._bg_probe(["blockdev"]),
+            lambda: self._bg_probe({"blockdev"}),
             lambda fut: self._probed(fut, True),
             )