diff --git a/rattail_tempmon/server.py b/rattail_tempmon/server.py
index 615bddc..507d02c 100644
--- a/rattail_tempmon/server.py
+++ b/rattail_tempmon/server.py
@@ -124,7 +124,8 @@ class TempmonServerDaemon(Daemon):
         cutoff = self.now - datetime.timedelta(seconds=delay + 60)
         online = False
         for probe in client.enabled_probes():
-            online = online or bool(self.check_readings_for_probe(session, probe, cutoff))
+            if self.check_readings_for_probe(session, probe, cutoff) and not online:
+                online = True
 
         # if client was previously marked online, but we have no "new"
         # readings, then let's look closer to see if it's been long enough to