diff --git a/libraries/dsp/si/src/python/si.py b/libraries/dsp/si/src/python/si.py
index 7254574cb4c906f39b910421c1f7dad41ce3529d..27f77be077eb429d6107e7ec39941ea92b6a2725 100755
--- a/libraries/dsp/si/src/python/si.py
+++ b/libraries/dsp/si/src/python/si.py
@@ -62,7 +62,7 @@ _parser = argparse.ArgumentParser(
     formatter_class=argparse.RawTextHelpFormatter)
 _parser.add_argument('--si', default=0, type=int, help='Spectral inversion control 0 = keep band, 1 = flip band')
 _parser.add_argument('--zi', default=0, type=int, help='Nyquist zone index 0 = 1st, 1 = 2nd, 2 = 3rd, etc')
-_parser.add_argument('-N', default=512, type=int, help='N_sub')
+_parser.add_argument('-N', default=512, type=int, help='Number of subbands')
 args = _parser.parse_args()
 
 spectral_inv = args.si