diff --git a/HISTORY.md b/HISTORY.md
index c859d549..d9085c83 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -2,7 +2,22 @@
 http://visjs.org
 
 
-## not yet released, version 2.0.0
+## 2014-06-19, version 2.0.1
+
+### Timeline
+
+- Throws an error when constructing without new keyword.
+
+### Graph
+
+- Throws an error when constructing without new keyword.
+
+### Graph3d
+
+- Throws an error when constructing without new keyword.
+
+
+## 2014-06-19, version 2.0.0
 
 ### Timeline
 
diff --git a/src/graph/Graph.js b/src/graph/Graph.js
index ee68da20..084d2261 100644
--- a/src/graph/Graph.js
+++ b/src/graph/Graph.js
@@ -10,6 +10,9 @@
  * @param {Object} options      Options
  */
 function Graph (container, data, options) {
+  if (!(this instanceof Graph)) {
+    throw new SyntaxError('Constructor must be called with the new operator');
+  }
 
   this._initializeMixinLoaders();
 
diff --git a/src/graph3d/Graph3d.js b/src/graph3d/Graph3d.js
index 21e3f5d1..c246b380 100644
--- a/src/graph3d/Graph3d.js
+++ b/src/graph3d/Graph3d.js
@@ -10,6 +10,10 @@
  * @param {Object} [options]
  */
 function Graph3d(container, data, options) {
+  if (!(this instanceof Graph3d)) {
+    throw new SyntaxError('Constructor must be called with the new operator');
+  }
+
   // create variables and set default values
   this.containerElement = container;
   this.width = '400px';
diff --git a/src/timeline/Timeline.js b/src/timeline/Timeline.js
index 38299f77..9706bc96 100644
--- a/src/timeline/Timeline.js
+++ b/src/timeline/Timeline.js
@@ -6,6 +6,10 @@
  * @constructor
  */
 function Timeline (container, items, options) {
+  if (!(this instanceof Timeline)) {
+    throw new SyntaxError('Constructor must be called with the new operator');
+  }
+
   var me = this;
   this.defaultOptions = {
     start: null,