4 files changed, 16 insertions, 10 deletions
diff --git a/packages/gitbook-core/src/models/File.js b/packages/gitbook-core/src/models/File.js
index 09dfc1b..6f44700 100644
--- a/packages/gitbook-core/src/models/File.js
+++ b/packages/gitbook-core/src/models/File.js
@@ -3,17 +3,20 @@ const { Record } = require('immutable');
 
 const DEFAULTS = {
     type:  '',
-    mtime: '',
+    mtime: new Date(),
     path:  ''
 };
 
 class File extends Record(DEFAULTS) {
-    constructor(file) {
+    constructor(file = {}) {
         if (typeof file === 'string') {
             file = { path: file };
         }
 
-        super(file);
+        super({
+            ...file,
+            mtime: new Date(file.mtime)
+        });
     }
 
     /**
diff --git a/packages/gitbook-core/src/shapes/Summary.js b/packages/gitbook-core/src/shapes/Summary.js
index 7efe4e0..f97e66c 100644
--- a/packages/gitbook-core/src/shapes/Summary.js
+++ b/packages/gitbook-core/src/shapes/Summary.js
@@ -1,6 +1,7 @@
 const React  = require('react');
+const { listOf } = require('react-immutable-proptypes');
+
 const {
-    arrayOf,
     shape
 } = React.PropTypes;
 
@@ -9,5 +10,5 @@ const Part = require('./SummaryPart');
 
 module.exports = shape({
     file:  File.isRequired,
-    parts: arrayOf(Part).isRequired
+    parts: listOf(Part).isRequired
 });
diff --git a/packages/gitbook-core/src/shapes/SummaryArticle.js b/packages/gitbook-core/src/shapes/SummaryArticle.js
index d13bb31..c5aa717 100644
--- a/packages/gitbook-core/src/shapes/SummaryArticle.js
+++ b/packages/gitbook-core/src/shapes/SummaryArticle.js
@@ -1,8 +1,9 @@
 /* eslint-disable no-use-before-define */
 
-const React  = require('react');
+const React = require('react');
+const { list } = require('react-immutable-proptypes');
+
 const {
-    arrayOf,
     string,
     number,
     shape
@@ -14,7 +15,7 @@ const Article = shape({
     path:     string,
     ref:      string,
     level:    string,
-    articles: arrayOf(Article)
+    articles: list
 });
 
 module.exports = Article;
diff --git a/packages/gitbook-core/src/shapes/SummaryPart.js b/packages/gitbook-core/src/shapes/SummaryPart.js
index 75d5602..769ddd1 100644
--- a/packages/gitbook-core/src/shapes/SummaryPart.js
+++ b/packages/gitbook-core/src/shapes/SummaryPart.js
@@ -1,6 +1,7 @@
 const React  = require('react');
+const { listOf } = require('react-immutable-proptypes');
+
 const {
-    arrayOf,
     string,
     shape
 } = React.PropTypes;
@@ -9,5 +10,5 @@ const Article = require('./SummaryArticle');
 
 module.exports = shape({
     title: string.isRequired,
-    articles: arrayOf(Article)
+    articles: listOf(Article)
 });