diff --git a/edosl0util/merge.py b/edosl0util/merge.py
index 20eebcec3525d2df271ca0e6f0d08d8ecfa92f35..46479f9acfcc72ddc3ccc15035e67269d60188f5 100644
--- a/edosl0util/merge.py
+++ b/edosl0util/merge.py
@@ -14,7 +14,7 @@ from collections import deque, OrderedDict
 
 LOG = logging.getLogger(__name__)
 
-VIIRS_APID_ORDER = [826, 821] + range(800, 821) + range(822,826)
+VIIRS_APID_ORDER = (826, 821) + tuple(range(800,821)) + tuple(range(822,826))
 
 class _Ptr(object):
     """