diff --git a/temperature_logger.py b/temperature_logger.py
index 129985d..4b7d4c7 100644
--- a/temperature_logger.py
+++ b/temperature_logger.py
@@ -73,6 +73,7 @@ class Monitor(Timer):
                 for reading in data[channel]:
                     (temperature, time_ms, overflow) = reading
                     point = self.make_point(
+                        serial,
                         channel,
                         temperature,
                         time_ms,
@@ -81,10 +82,10 @@ class Monitor(Timer):
                     points.append(point)
         self.idb.commit(points)
 
-    def make_point(self, channel, temperature, time_ms, overflow):
+    def make_point(self, serial, channel, temperature, time_ms, overflow):
         json_body = {
             "measurement": "temperature",
-            "tags": {"channel": channel},
+            "tags": {"channel": channel, "tc08-serial": serial},
             "time": time_ms,
             "fields": {"temperature": temperature, "overflow": overflow},
         }