--- a/weatherlog/reader.py	Fri Sep 27 21:28:38 2019 -0400
+++ b/weatherlog/reader.py	Fri Sep 27 21:36:16 2019 -0400
@@ -23,15 +23,15 @@
 class Reading(object):
     """A single reading from a temperature/humidity sensor."""
 
-    # The timestamp of the reading.
-    timestamp = attr.ib(type=datetime.datetime, factory=_utc_now)
-
     # The temperature, in degrees Celsius.
     temp_c = attr.ib(type=float)
 
     # The relative humidity, in percent.
     rh_pct = attr.ib(type=float)
 
+    # The timestamp of the reading.
+    timestamp = attr.ib(type=datetime.datetime, factory=_utc_now)
+
 
 class Reader(metaclass=abc.ABCMeta):
     """Interface for a thing which reads temperatures."""