diff --git a/externs/olx.js b/externs/olx.js
index 41eada26e2..5d9bd288f5 100644
--- a/externs/olx.js
+++ b/externs/olx.js
@@ -5257,7 +5257,7 @@ olx.source.ImageVectorOptions.prototype.style;
  *     operation: (ol.RasterOperation|undefined),
  *     lib: (Object|undefined),
  *     threads: (number|undefined),
- *     operationType: (ol.RasterOperationType|undefined)}}
+ *     operationType: (ol.source.Raster.OperationType|undefined)}}
  * @api
  */
 olx.source.RasterOptions;
@@ -5305,7 +5305,7 @@ olx.source.RasterOptions.prototype.threads;
  * `'pixel'` operations are assumed, and operations will be called with an
  * array of pixels from input sources.  If set to `'image'`, operations will
  * be called with an array of ImageData objects from input sources.
- * @type {ol.RasterOperationType|undefined}
+ * @type {ol.source.Raster.OperationType|undefined}
  * @api
  */
 olx.source.RasterOptions.prototype.operationType;
diff --git a/src/ol/source/raster.js b/src/ol/source/raster.js
index 8ed70b96e6..ae085fa1cc 100644
--- a/src/ol/source/raster.js
+++ b/src/ol/source/raster.js
@@ -1,5 +1,4 @@
 goog.provide('ol.source.Raster');
-goog.provide('ol.RasterOperationType');
 
 goog.require('ol');
 goog.require('ol.transform');
@@ -21,16 +20,6 @@ goog.require('ol.source.State');
 goog.require('ol.source.Tile');
 
 
-/**
- * Raster operation type. Supported values are `'pixel'` and `'image'`.
- * @enum {string}
- */
-ol.RasterOperationType = {
-  PIXEL: 'pixel',
-  IMAGE: 'image'
-};
-
-
 /**
  * @classdesc
  * A source that transforms data from any number of input sources using an array
@@ -53,10 +42,10 @@ ol.source.Raster = function(options) {
 
   /**
    * @private
-   * @type {ol.RasterOperationType}
+   * @type {ol.source.Raster.OperationType}
    */
   this.operationType_ = options.operationType !== undefined ?
-      options.operationType : ol.RasterOperationType.PIXEL;
+      options.operationType : ol.source.Raster.OperationType.PIXEL;
 
   /**
    * @private
@@ -160,7 +149,7 @@ ol.inherits(ol.source.Raster, ol.source.Image);
 ol.source.Raster.prototype.setOperation = function(operation, opt_lib) {
   this.worker_ = new ol.ext.pixelworks.Processor({
     operation: operation,
-    imageOps: this.operationType_ === ol.RasterOperationType.IMAGE,
+    imageOps: this.operationType_ === ol.source.Raster.OperationType.IMAGE,
     queue: 1,
     lib: opt_lib,
     threads: this.threads_
@@ -512,3 +501,13 @@ ol.source.Raster.EventType = {
    */
   AFTEROPERATIONS: 'afteroperations'
 };
+
+
+/**
+ * Raster operation type. Supported values are `'pixel'` and `'image'`.
+ * @enum {string}
+ */
+ol.source.Raster.OperationType = {
+  PIXEL: 'pixel',
+  IMAGE: 'image'
+};