diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 9ece274..9411477 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -1599,6 +1599,13 @@
 difficulties (such as may happen with large lex files).
 
 
+LIFELINES				*lifelines.vim* *ft-lifelines-syntax*
+
+To highlight deprecated functions as errors, add in your .vimrc: >
+
+	:let g:lifelines_deprecated = 1
+<
+
 LISP						*lisp.vim* *ft-lisp-syntax*
 
 The lisp syntax highlighting provides two options: >