diff --git a/docs/realm.js b/docs/realm.js
index 2bd4c314..be25e46b 100644
--- a/docs/realm.js
+++ b/docs/realm.js
@@ -95,7 +95,7 @@ class Realm {
      * Open a realm asynchronously with a promise. If the realm is synced, it will be fully 
      * synchronized before it is available.
      * @param {Realm~Configuration} config 
-     * @returns {Promise} - a promise that will be resolved with the realm instance when it's available.
+     * @returns {ProgressPromise} - a promise that will be resolved with the realm instance when it's available.
      */
     static open(config) {}
 
@@ -104,9 +104,10 @@ class Realm {
      * synchronized before it is available.
      * @param {Realm~Configuration} config 
      * @param  {callback(error, realm)} - will be called when the realm is ready.
+     * @param  {callback(transferred, transferable)} [progressCallback] - an optional callback for download progress notifications
      * @throws {Error} If anything in the provided `config` is invalid.
      */
-    static openAsync(config, callback) {}
+    static openAsync(config, callback, progressCallback) {}
 
     /**
      * Closes this Realm so it may be re-opened with a newer schema version.
diff --git a/lib/extensions.js b/lib/extensions.js
index 3ec8f6cf..1bc9c8d0 100644
--- a/lib/extensions.js
+++ b/lib/extensions.js
@@ -76,13 +76,7 @@ module.exports = function(realmConstructor) {
             return promise;
         },
 
-        openAsync(config, progressCallback, callback) {
-
-            if (!callback) {
-                callback = progressCallback;
-                progressCallback = null;
-            }
-
+        openAsync(config, callback, progressCallback) {
             realmConstructor._waitForDownload(config,
                 (syncSession) => {
                     if (progressCallback) {
diff --git a/lib/index.d.ts b/lib/index.d.ts
index 22e65558..a49e6e6c 100644
--- a/lib/index.d.ts
+++ b/lib/index.d.ts
@@ -448,10 +448,10 @@ declare class Realm {
     /**
      * Open a realm asynchronously with a callback. If the realm is synced, it will be fully synchronized before it is available.
      * @param {Configuration} config 
-     * @param {ProgressNotificationCallback} progressCallback? a progress notification callback for 'download' direction and 'forCurrentlyOutstandingWork' mode 
      * @param {Function} callback will be called when the realm is ready.
+     * @param {ProgressNotificationCallback} progressCallback? a progress notification callback for 'download' direction and 'forCurrentlyOutstandingWork' mode 
      */
-    static openAsync(config: Realm.Configuration, progressCallback?: Realm.Sync.ProgressNotificationCallback, callback: (error: any, realm: Realm) => void): void
+    static openAsync(config: Realm.Configuration, callback: (error: any, realm: Realm) => void, progressCallback?: Realm.Sync.ProgressNotificationCallback): void
 
     /**
      * Delete the Realm file for the given configuration.
diff --git a/tests/js/session-tests.js b/tests/js/session-tests.js
index 153bd6e9..46f6c994 100644
--- a/tests/js/session-tests.js
+++ b/tests/js/session-tests.js
@@ -626,9 +626,6 @@ module.exports = {
                         let progressCalled = false;
                         
                         Realm.openAsync(config, 
-                            (transferred, total) => {
-                                progressCalled = true;
-                            }, 
                             (error, realm) => {
                                 if (error) {
                                     reject(error);
@@ -637,6 +634,9 @@ module.exports = {
                                 
                                 TestCase.assertTrue(progressCalled);
                                 resolve();
+                            },
+                            (transferred, total) => {
+                                progressCalled = true;
                             });
 
                         setTimeout(function() {