diff --git a/modules/util/viirs.py b/modules/util/viirs.py
index 95abfaea260340c3e391786c861ff73126071b5c..2b4ab7932a211cff6892ff133c974e919137095b 100644
--- a/modules/util/viirs.py
+++ b/modules/util/viirs.py
@@ -18,7 +18,7 @@ def run_all(directory):
     for idx, mfile in enumerate(mod_files):
         if idx % 2 == 0:
             w_o_ext, ext = os.path.splitext(mfile)
-            ifile = w_o_ext+'uwssec'+ext
+            ifile = w_o_ext+'.uwssec'+ext
             run(mfile, ifile, mod_tiles, img_tiles)
 
     mod_nda = np.stack(mod_tiles)