diff --git a/scripts/script.js b/scripts/script.js
index 5cc5967..a5ff892 100755
--- a/scripts/script.js
+++ b/scripts/script.js
@@ -7,6 +7,12 @@
l = slides.length, i;
for (i = 0; i < l; i++) {
+ // Slide ID's are optional. In case of missing ID we set it to the
+ // slide number
+ if (!slides[i].id) {
+ slides[i].id = i + 1;
+ }
+
slideList.push({
id: slides[i].id,
hasInnerNavigation: null !== slides[i].querySelector('.next')