diff --git a/src/packaging.js b/src/packaging.js
index 396b5d4..f20f918 100644
--- a/src/packaging.js
+++ b/src/packaging.js
@@ -167,6 +167,7 @@ class Packaging {
 			// var manifestPropArray = manifestProps.length ? manifestProps.split(" ") : [];
 
 			var itemref = {
+				"id" : item.getAttribute("id"),
 				"idref" : idref,
 				"linear" : item.getAttribute("linear") || "yes",
 				"properties" : propArray,
diff --git a/src/spine.js b/src/spine.js
index 519b67c..ffe51e1 100644
--- a/src/spine.js
+++ b/src/spine.js
@@ -51,7 +51,7 @@ class Spine {
 			var spineItem;
 
 			item.index = index;
-			item.cfiBase = this.epubcfi.generateChapterComponent(this.spineNodeIndex, item.index, item.idref);
+			item.cfiBase = this.epubcfi.generateChapterComponent(this.spineNodeIndex, item.index, item.id);
 
 			if (item.href) {
 				item.url = resolver(item.href, true);