diff --git a/doc/man/cdist-reference.text.sh b/doc/man/cdist-reference.text.sh
index c205bdcc..7196c3b3 100755
--- a/doc/man/cdist-reference.text.sh
+++ b/doc/man/cdist-reference.text.sh
@@ -166,6 +166,11 @@ changed::
 
 ENVIRONMENT VARIABLES
 ---------------------
+__debug::
+   If this variable is setup, cdist runs in debug mode.
+   You can use this information, to only output stuff in debug
+   mode as well.
+   Available for: initial manifest, type manifest
 __explorer::
    Directory that contains all global explorers.
    Available for: explorer