diff --git a/geomagio/iaga2002/IAGA2002Parser.py b/geomagio/iaga2002/IAGA2002Parser.py
index eb8a1c0e7885920edc8ebf2f7a6e973c55d98cf7..d3044082ccb4a7dbb6d7db220f9d008bb17213f1 100644
--- a/geomagio/iaga2002/IAGA2002Parser.py
+++ b/geomagio/iaga2002/IAGA2002Parser.py
@@ -8,6 +8,9 @@ from datetime import datetime
 EIGHTS = numpy.float64('88888.88')
 NINES = numpy.float64('99999.99')
 
+# placeholder channel name used when less than 4 channels are being written.
+EMPTY_CHANNEL = 'NUL'
+
 
 class IAGA2002Parser(object):
     """IAGA2002 parser.
@@ -166,13 +169,12 @@ class IAGA2002Parser(object):
         self.parse_comments()
         self.times = self._parsedata[0]
         for channel, data in zip(self.channels, self._parsedata[1:]):
-            #ignore empty channels
+            # ignore "empty" channels
+            if channel == EMPTY_CHANNEL:
+                continue
             data = numpy.array(data, dtype=numpy.float64)
             data[data == EIGHTS] = numpy.nan
             data[data == NINES] = numpy.nan
-            # filter empty values
-            if data.count(numpy.nan) == len(data):
-                continue
             self.data[channel] = data
         self._parsedata = None
 
diff --git a/geomagio/iaga2002/IAGA2002Writer.py b/geomagio/iaga2002/IAGA2002Writer.py
index 7a05d27d4d445b3e21364296a2a59389e6ffb64f..0097e1e505dc05aae65f98b9a40cdb66c55caee8 100644
--- a/geomagio/iaga2002/IAGA2002Writer.py
+++ b/geomagio/iaga2002/IAGA2002Writer.py
@@ -14,8 +14,10 @@ class IAGA2002Writer(object):
     """IAGA2002 writer.
     """
 
-    def __init__(self, empty_value=IAGA2002Parser.NINES):
+    def __init__(self, empty_value=IAGA2002Parser.NINES,
+            empty_channel=IAGA2002Parser.EMPTY_CHANNEL):
         self.empty_value = empty_value
+        self.empty_channel = empty_channel
 
     def write(self, out, timeseries, channels):
         """write timeseries to iaga file
@@ -232,7 +234,7 @@ class IAGA2002Writer(object):
 
     def _pad_to_four_channels(self, timeseries, channels):
         for x in range(len(channels), 4):
-            channel = 'NUL'
+            channel = self.empty_channel
             channels.append(channel)
             timeseries += create_empty_trace(timeseries[0], channel)