diff --git a/externs/olx.js b/externs/olx.js
index aa86865178..610019c424 100644
--- a/externs/olx.js
+++ b/externs/olx.js
@@ -515,97 +515,6 @@ olx.source.TileDebugOptions.prototype.tileGrid;
 olx.source.TileDebugOptions.prototype.wrapX;
 
 
-/**
- * @typedef {{attributions: (ol.AttributionLike|undefined),
- *     cacheSize: (number|undefined),
- *     crossOrigin: (null|string|undefined),
- *     maxZoom: (number|undefined),
- *     opaque: (boolean|undefined),
- *     reprojectionErrorThreshold: (number|undefined),
- *     tileLoadFunction: (ol.TileLoadFunctionType|undefined),
- *     url: (string|undefined),
- *     wrapX: (boolean|undefined)}}
- */
-olx.source.OSMOptions;
-
-
-/**
- * Attributions.
- * @type {ol.AttributionLike|undefined}
- * @api
- */
-olx.source.OSMOptions.prototype.attributions;
-
-
-/**
- * Cache size. Default is `2048`.
- * @type {number|undefined}
- * @api
- */
-olx.source.OSMOptions.prototype.cacheSize;
-
-
-/**
- * The `crossOrigin` attribute for loaded images.  Note that you must provide a
- * `crossOrigin` value if you are using the WebGL renderer or if you want to
- * access pixel data with the Canvas renderer.  See
- * {@link https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image}
- * for more detail.
- *
- * Default is `anonymous`.
- * @type {null|string|undefined}
- * @api
- */
-olx.source.OSMOptions.prototype.crossOrigin;
-
-
-/**
- * Max zoom. Default is `19`.
- * @type {number|undefined}
- * @api
- */
-olx.source.OSMOptions.prototype.maxZoom;
-
-
-/**
- * Whether the layer is opaque. Default is `true`.
- * @type {boolean|undefined}
- * @api
- */
-olx.source.OSMOptions.prototype.opaque;
-
-
-/**
- * Maximum allowed reprojection error (in pixels). Default is `0.5`.
- * Higher values can increase reprojection performance, but decrease precision.
- * @type {number|undefined}
- * @api
- */
-olx.source.OSMOptions.prototype.reprojectionErrorThreshold;
-
-
-/**
- * Optional function to load a tile given a URL. The default is
- * ```js
- * function(imageTile, src) {
- *   imageTile.getImage().src = src;
- * };
- * ```
- * @type {ol.TileLoadFunctionType|undefined}
- * @api
- */
-olx.source.OSMOptions.prototype.tileLoadFunction;
-
-
-/**
- * URL template. Must include `{x}`, `{y}` or `{-y}`, and `{z}` placeholders.
- * Default is `https://{a-c}.tile.openstreetmap.org/{z}/{x}/{y}.png`.
- * @type {string|undefined}
- * @api
- */
-olx.source.OSMOptions.prototype.url;
-
-
 /**
  * @typedef {{sources: Array.<ol.source.Source>,
  *     operation: (ol.RasterOperation|undefined),
diff --git a/src/ol/source/OSM.js b/src/ol/source/OSM.js
index a583bc5ffc..1aae16eb9e 100644
--- a/src/ol/source/OSM.js
+++ b/src/ol/source/OSM.js
@@ -17,13 +17,37 @@ export const ATTRIBUTION = '&copy; ' +
       'contributors.';
 
 
+/**
+ * @typedef {Object} Options
+ * @property {ol.AttributionLike} [attributions] Attributions.
+ * @property {number} [cacheSize=2048] Cache size.
+ * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
+ * you must provide a `crossOrigin` value if you are using the WebGL renderer or if you want to
+ * access pixel data with the Canvas renderer.  See
+ * {@link https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image} for more detail.
+ * @property {number} [maxZoom=19] Max zoom.
+ * @property {boolean} [opaque=true] Whether the layer is opaque.
+ * @property {number} [reprojectionErrorThreshold=1.5] Maximum allowed reprojection error (in pixels).
+ * Higher values can increase reprojection performance, but decrease precision.
+ * @property {ol.TileLoadFunctionType} [tileLoadFunction] Optional function to load a tile given a URL. The default is
+ * ```js
+ * function(imageTile, src) {
+ *   imageTile.getImage().src = src;
+ * };
+ * ```
+ * @property {string} [url='https://{a-c}.tile.openstreetmap.org/{z}/{x}/{y}.png'] URL template.
+ * Must include `{x}`, `{y}` or `{-y}`, and `{z}` placeholders.
+ * @property {boolean} [wrapX=true] Whether to wrap the world horizontally.
+ */
+
+
 /**
  * @classdesc
  * Layer source for the OpenStreetMap tile server.
  *
  * @constructor
  * @extends {ol.source.XYZ}
- * @param {olx.source.OSMOptions=} opt_options Open Street Map options.
+ * @param {module:ol/source/OSM~Options=} [opt_options] Open Street Map options.
  * @api
  */
 const OSM = function(opt_options) {