diff --git a/visidata/loaders/fixed_width.py b/visidata/loaders/fixed_width.py
index 6f74fb1ef..418791ed2 100644
--- a/visidata/loaders/fixed_width.py
+++ b/visidata/loaders/fixed_width.py
@@ -110,3 +110,5 @@ def save_fixed(vd, p, *vsheets):
                     for col, val in dispvals.items():
                         fp.write(('{0:%s%s.%s} ' % ('>' if vd.isNumeric(col) else '<', widths[col], widths[col])).format(val))
                     fp.write('\n')
+
+FixedWidthColumnsSheet.options.null_value = ''    # the file format cannot contain None, so use empty string instead