diff --git a/cmdeploy/src/cmdeploy/tests/online/test_1_basic.py b/cmdeploy/src/cmdeploy/tests/online/test_1_basic.py
index c8525125..af57816e 100644
--- a/cmdeploy/src/cmdeploy/tests/online/test_1_basic.py
+++ b/cmdeploy/src/cmdeploy/tests/online/test_1_basic.py
@@ -218,7 +218,7 @@ def test_expunged(remote, chatmail_config):
     ]
     outdated_days = int(chatmail_config.delete_large_after) + 1
     find_cmds.append(
-        "find {chatmail_config.mailboxes_dir} -path '*/cur/*' -mtime +{outdated_days} -size +200k -type f"
+        f"find {chatmail_config.mailboxes_dir} -path '*/cur/*' -mtime +{outdated_days} -size +200k -type f"
     )
     for cmd in find_cmds:
         for line in remote.iter_output(cmd):