diff --git a/doc/advopt.txt b/doc/advopt.txt
index 75260baad3..5ddd064ef6 100644
--- a/doc/advopt.txt
+++ b/doc/advopt.txt
@@ -55,8 +55,6 @@ Advanced options:
   --clibdir:DIR             modify the linker library search path
   --clib:LIBNAME            link an additional C library
                             (you should omit platform-specific extensions)
-  --genMapping              generate a mapping file containing
-                            (Nim, mangled) identifier pairs
   --project                 document the whole project (doc2)
   --docSeeSrcUrl:url        activate 'see source' for doc and doc2 commands
                             (see doc.item.seesrc in config/nimdoc.cfg)