diff --git a/book.js b/book.js
index 86563e1..a2a058b 100644
--- a/book.js
+++ b/book.js
@@ -1,5 +1,5 @@
 module.exports = {
     title: 'Unprotocols RFCs',
     gitbook: '>=3.0.0',
-    plugins: ['coss']
+    plugins: ['coss@1.0.4']
 };