diff --git a/wetb/prepost/windIO.py b/wetb/prepost/windIO.py
index 09f3c356ef2113d258d9436494bc392cb5b7017d..2e2299173bc911c3b8f1b2aa2dc46f06ae6abbbd 100755
--- a/wetb/prepost/windIO.py
+++ b/wetb/prepost/windIO.py
@@ -96,6 +96,10 @@ class LoadResults:
                 ch_dict[tag]['units']
 
     """
+    # ch_df columns, these are created by LoadResults._unified_channel_names
+    cols = set(['bearing_name', 'sensortag', 'bodyname', 'chi', 'component',
+                'pos', 'coord', 'sensortype', 'radius', 'blade_nr', 'units',
+                'output_type', 'io_nr', 'io', 'dll', 'azimuth', 'flap_nr'])
 
     # start with reading the .sel file, containing the info regarding
     # how to read the binary file and the channel information