diff --git a/src/doc.rs b/src/doc.rs
index 9776321..da47a9e 100644
--- a/src/doc.rs
+++ b/src/doc.rs
@@ -48,7 +48,7 @@ pub struct NavPoint {
     /// nested navpoints
     pub children: Vec<NavPoint>,
     /// the order in the toc
-    pub play_order: usize,
+    pub play_order: Option<usize>,
 }
 
 impl Ord for NavPoint {
@@ -983,7 +983,9 @@ impl<R: Read + Seek> EpubDoc<R> {
             if item.name.local_name != "navPoint" {
                 continue;
             }
-            let play_order = item.get_attr("playOrder").and_then(|n| n.parse().ok());
+            let play_order = item
+                .get_attr("playOrder")
+                .and_then(|n| n.parse::<usize>().ok());
             let content = item
                 .find("content")
                 .and_then(|c| c.borrow().get_attr("src").map(|p| self.root_base.join(p)));
@@ -995,12 +997,12 @@ impl<R: Read + Seek> EpubDoc<R> {
                     .and_then(|t| t.borrow().text.clone())
             });
 
-            if let (Some(o), Some(c), Some(l)) = (play_order, content, label) {
+            if let (order, Some(content_path), Some(label_text)) = (play_order, content, label) {
                 let navpoint = NavPoint {
-                    label: l.clone(),
-                    content: c.clone(),
+                    label: label_text.clone(),
+                    content: content_path.clone(),
                     children: self.get_navpoints(&item),
-                    play_order: o,
+                    play_order: order,
                 };
                 navpoints.push(navpoint);
             }
diff --git a/tests/doc.rs b/tests/doc.rs
index 6acc79d..3626e60 100644
--- a/tests/doc.rs
+++ b/tests/doc.rs
@@ -131,7 +131,7 @@ fn toc_test() {
     for nav in doc.toc.iter() {
         let chapter = doc.resource_uri_to_chapter(&nav.content);
         assert!(chapter.is_some());
-        assert_eq!(nav.play_order, chapter.unwrap());
+        assert_eq!(nav.play_order.unwrap(), chapter.unwrap());
     }
 }
 
@@ -144,6 +144,24 @@ fn toc_title_test() {
     assert!(doc.toc_title == "Todo es mío");
 }
 
+#[test]
+fn test_toc_play_order() {
+    let doc = EpubDoc::new("test.epub");
+    assert!(doc.is_ok());
+    let doc = doc.unwrap();
+
+    assert!(!doc.toc.is_empty());
+    let mut previous_order = None;
+    for nav in doc.toc.iter() {
+        nav.play_order.map(|order| {
+            if let Some(prev) = previous_order {
+                assert!(prev < order, "Play order is not increasing");
+            }
+            previous_order = Some(order);
+        });
+    }
+}
+
 #[test]
 fn version_test() {
     let doc = EpubDoc::new("test.epub");