diff --git a/changelog.txt b/changelog.txt
index 1ea02eb6..45fe8038 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -3,6 +3,7 @@ OPENSEADRAGON CHANGELOG
 
 1.0.0: (in progress)
 
+* BREAKING CHANGE: TileSource 'ready' event handler signature changed for consistency to 'handlerMethod( eventSource, eventData)' (#239)
 * BREAKING CHANGE: Renamed EventHandler to EventSource (#225)
 * BREAKING CHANGE: MouseTracker event handler method signatures changed to 'handlerMethod( tracker, eventData)' (#23)
 * BREAKING CHANGE: Event names changed for consistency: changed to lower case, compound names hyphenated, and "on" prefixes removed (#226):
diff --git a/src/tilesource.js b/src/tilesource.js
index 9352487e..641f0e65 100644
--- a/src/tilesource.js
+++ b/src/tilesource.js
@@ -117,15 +117,8 @@ $.TileSource = function( width, height, tileSize, tileOverlap, minLevel, maxLeve
     for ( i = 0; i < arguments.length; i++ ) {
         if ( $.isFunction( arguments[ i ] ) ) {
             callback = arguments[ i ];
-            // TODO Send generic object wrapping readySource as a property (breaking change)
-            // TODO Maybe placeHolderSource should be passed to callback as well for consistency
-            //      with event handler signature?
-            //  Should be this (although technically it works as-is):
-            //this.addHandler( 'ready', function ( placeHolderSource, placeHolderArgs ) {
-            //    callback( placeHolderArgs );
-            //} );
-            this.addHandler( 'ready', function ( placeHolderSource, readySource ) {
-                callback( readySource );
+            this.addHandler( 'ready', function ( placeHolderSource, placeHolderEventData ) {
+                callback( placeHolderSource, placeHolderEventData );
             } );
             //only one callback per constructor
             break;
@@ -308,10 +301,7 @@ $.TileSource.prototype = {
             options = $TileSource.prototype.configure.apply( _this, [ data, url ]);
             readySource = new $TileSource( options );
             _this.ready = true;
-            // TODO Send generic object wrapping readySource as a property (breaking change)
-            //  Should be this:
-            //_this.raiseEvent( 'ready', { tileSource: readySource } );
-            _this.raiseEvent( 'ready', readySource );
+            _this.raiseEvent( 'ready', { tileSource: readySource } );
         };
 
         if( url.match(/\.js$/) ){
diff --git a/src/viewer.js b/src/viewer.js
index 65199316..ecd8560f 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -438,8 +438,8 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
         setTimeout(function(){
             if ( $.type( tileSource ) == 'string') {
                 //If its still a string it means it must be a url at this point
-                tileSource = new $.TileSource( tileSource, function( readySource ){
-                    openTileSource( _this, readySource );
+                tileSource = new $.TileSource( tileSource, function( eventSource, eventData ){
+                    openTileSource( _this, eventData.tileSource );
                 });
                 tileSource.addHandler( 'open-failed', function ( name, args ) {
                     _this.raiseEvent( 'open-failed', args );