diff --git a/data/epub.css b/data/epub.css
index b0512b7d82c4..4ccb3c37942f 100644
--- a/data/epub.css
+++ b/data/epub.css
@@ -56,7 +56,7 @@ h5 {
   margin: 1.1em 0 0 0;
   font-size: 1.1em;
 }
-h5 {
+h6 {
   font-size: 1em;
 }
 h1, h2, h3, h4, h5, h6 {