diff --git a/doc/internals/filters.txt b/doc/internals/filters.txt
index 7b5144a..ce054df 100644
--- a/doc/internals/filters.txt
+++ b/doc/internals/filters.txt
@@ -1,5 +1,5 @@
                    -----------------------------------------
-                          Filters Guide - version 1.8
+                          Filters Guide - version 1.9
                           ( Last update: 2017-07-27 )
                    ------------------------------------------
                           Author : Christopher Faulet