diff --git a/python/obitools3/parsers/ngsfilter.pyx b/python/obitools3/parsers/ngsfilter.pyx
index 1212d36..fbe3e89 100755
--- a/python/obitools3/parsers/ngsfilter.pyx
+++ b/python/obitools3/parsers/ngsfilter.pyx
@@ -54,7 +54,7 @@ def ngsfilterIterator(lineiterator,
     new_lines.append(header)
         
     for line in all_lines:
-        split_line = line.split(sep)
+        split_line = line.split()
         tags = split_line.pop(2)
         tags = tags.split(b":")
         if len(tags) == 1:          # Forward and reverse tags are the same