diff --git a/nms.6 b/nms.6
index 2d41775..10a6676 100644
--- a/nms.6
+++ b/nms.6
@@ -11,6 +11,9 @@ nms [options]
 .B -a
 sets the auto-decrypt flag, decryption sequence starts without requiring a key press.
 .TP
+.B -s
+sets the mask blanks flag. Blank spaces will be encrypted and decrypted.
+.TP
 .B -c
 clear the screen prior to printing any output
 .TP