diff --git a/Doc/lib/librotor.tex b/Doc/lib/librotor.tex
index de99b461cb4..0f848e08d3d 100644
--- a/Doc/lib/librotor.tex
+++ b/Doc/lib/librotor.tex
@@ -4,6 +4,8 @@
 \declaremodule{builtin}{rotor}
 \modulesynopsis{Enigma-like encryption and decryption.}
 
+\deprecated{2.3}{The encryption algorithm is insecure.}
+
 
 This module implements a rotor-based encryption algorithm, contributed by
 Lance Ellinghouse\index{Ellinghouse, Lance}.  The design is derived