diff --git a/epubfile.py b/epubfile.py
index 6568f4c..017818c 100644
--- a/epubfile.py
+++ b/epubfile.py
@@ -1250,6 +1250,11 @@ merge:
     > epubfile.py merge book1.epub book2.epub --output final.epub <flags>
 
     flags:
+    --demote_headers
+        All h1 in the book will be demoted to h2, and so forth. So that the
+        headerfiles are the only h1s and the table of contents will generate
+        with a good hierarchy.
+
     --headerfile:
         Add a file before each book with an <h1> containing its title.