diff --git a/Gruntfile.js b/Gruntfile.js
index 95fa132915f06406f0ef6c89f3f8577d8615c32f..277681f8c79645162a82d7f05813bc6638e1a4ea 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -1,5 +1,9 @@
 const readdirp = require("readdirp");
-const { extname } = require("path");
+const {
+  extname,
+  dirname,
+  posix: { relative }
+} = require("path");
 
 module.exports = grunt => {
   const PUBLIC_HOST = process.env.PUBLIC_HOST || "localhost";
@@ -60,6 +64,7 @@ module.exports = grunt => {
             "--toc",
             `--toc-depth=${TOC_DEPTH}`,
             `--slide-level=${SLIDE_LEVEL}`,
+            `--variable=revealjs-url:${relative(dirname(pres), "./reveal.js")}`,
             "--variable=theme:irstea",
             "--variable=history:true",
             env === "dev" &&