diff --git a/src/objectliterals.jsdoc b/src/objectliterals.jsdoc
index 60792392ac..9a7afa90bc 100644
--- a/src/objectliterals.jsdoc
+++ b/src/objectliterals.jsdoc
@@ -711,7 +711,7 @@
  *     on.
  * @property {Array.<number>|undefined} resolutions Resolutions. If specified,
  *     new canvases will be created for these resolutions only.
- * @property {ol.source.State|undefined} state Source state.
+ * @property {ol.source.State|string|undefined} state Source state.
  */
 
 /**
@@ -836,7 +836,7 @@
  * @property {Array.<ol.Feature>|undefined} features Features.
  * @property {string|undefined} logo Logo.
  * @property {ol.proj.ProjectionLike} projection Projection.
- * @property {ol.source.State|undefined} state State.
+ * @property {ol.source.State|string|undefined} state State.
  */
 
 /**
diff --git a/src/ol/source/imagesource.js b/src/ol/source/imagesource.js
index 51b8f1f0b3..4e8ea558d3 100644
--- a/src/ol/source/imagesource.js
+++ b/src/ol/source/imagesource.js
@@ -15,7 +15,7 @@ goog.require('ol.source.Source');
  *            logo: (string|undefined),
  *            projection: ol.proj.ProjectionLike,
  *            resolutions: (Array.<number>|undefined),
- *            state: (ol.source.State|undefined)}}
+ *            state: (ol.source.State|string|undefined)}}
  */
 ol.source.ImageOptions;
 
diff --git a/src/ol/source/source.js b/src/ol/source/source.js
index 03f0fa027e..c9039bbbf7 100644
--- a/src/ol/source/source.js
+++ b/src/ol/source/source.js
@@ -23,7 +23,7 @@ ol.source.State = {
  *            extent: (ol.Extent|undefined),
  *            logo: (string|undefined),
  *            projection: ol.proj.ProjectionLike,
- *            state: (ol.source.State|undefined)}}
+ *            state: (ol.source.State|string|undefined)}}
  * @todo stability experimental
  */
 ol.source.SourceOptions;
@@ -72,7 +72,7 @@ ol.source.Source = function(options) {
    * @type {ol.source.State}
    */
   this.state_ = goog.isDef(options.state) ?
-      options.state : ol.source.State.READY;
+      /** @type {ol.source.State} */ (options.state) : ol.source.State.READY;
 
 };
 goog.inherits(ol.source.Source, ol.Observable);