diff --git a/book.asciidoc b/book.asciidoc
index d6197cee0..cf73ad30e 100644
--- a/book.asciidoc
+++ b/book.asciidoc
@@ -1,3 +1,4 @@
+:title-separator: |
 :bookseries: animal
 :es_build:   1
 :ref: https://www.elastic.co/guide/en/elasticsearch/reference/5.6