diff --git a/js/isotope.js b/js/isotope.js
index 8496179..0db2637 100644
--- a/js/isotope.js
+++ b/js/isotope.js
@@ -268,13 +268,17 @@ function isotopeDefinition( Outlayer, getSize, matchesSelector, Item, LayoutMode
    * @public
    */
   Isotope.prototype.updateSortData = function( elems ) {
+    // get items
+    var items;
+    if ( elems ) {
+      elems = makeArray( elems );
+      items = this.getItems( elems );
+    } else {
+      // update all items if no elems provided
+      items = this.items;
+    }
+
     this._getSorters();
-    // update item sort data
-    // default to all items if none are passed in
-    elems = makeArray( elems );
-    var items = this.getItems( elems );
-    // if no items found, update all items
-    items = items.length ? items : this.items;
     this._updateItemsSortData( items );
   };
 
@@ -291,7 +295,10 @@ function isotopeDefinition( Outlayer, getSize, matchesSelector, Item, LayoutMode
    * @private
    */
   Isotope.prototype._updateItemsSortData = function( items ) {
-    for ( var i=0, len = items.length; i < len; i++ ) {
+    // do not update if no items
+    var len = items && items.length;
+
+    for ( var i=0; len && i < len; i++ ) {
       var item = items[i];
       item.updateSortData();
     }
diff --git a/test/get-sort-data.js b/test/get-sort-data.js
deleted file mode 100644
index ce6091f..0000000
--- a/test/get-sort-data.js
+++ /dev/null
@@ -1,24 +0,0 @@
-test( 'getSortData', function() {
-
-  'use strict';
-
-  var iso = new Isotope( '#get-sort-data', {
-    layoutMode: 'fitRows',
-    getSortData: {
-      ninjaTurtle: '[data-ninja-turtle]',
-      fruit: 'span.fruit',
-      b: 'b parseFloat',
-      i: 'i parseInt',
-      bbroke: 'b foobar'
-    }
-  });
-
-  var item = iso.items[0];
-
-  equal( item.sortData.ninjaTurtle, 'leonardo', '[data-attr] shorthand' );
-  equal( item.sortData.fruit, 'watermelon', 'query selector shorthand' );
-  equal( item.sortData.b, 3.14, 'parseFloat parser' );
-  equal( item.sortData.i, 42, 'parseInt parser' );
-  equal( item.sortData.bbroke, '3.14', 'default nonparser' );
-
-});
diff --git a/test/index.html b/test/index.html
index a54bd85..51032e6 100644
--- a/test/index.html
+++ b/test/index.html
@@ -21,7 +21,7 @@
 <script src="../bower_components/outlayer/outlayer.js"></script>
 <script src="../bower_components/masonry/masonry.js"></script>
 
-<script src="../bower_components/jquery/dist/jquery.js"></script>
+<script src="../bower_components/jquery/jquery.js"></script>
 
 <script src="../js/item.js"></script>
 <script src="../js/layout-mode.js"></script>
@@ -33,7 +33,7 @@
 
 <script src="helpers.js"></script>
 <script src="sorting.js"></script>
-<script src="get-sort-data.js"></script>
+<script src="sort-data.js"></script>
 <script src="filtering.js"></script>
 <script src="layout-complete.js"></script>
 <script src="get-segment-size.js"></script>
@@ -63,11 +63,16 @@
   <h2>getSortData</h2>
 
   <div id="get-sort-data" class="container">
-    <div class="item" data-ninja-turtle="leonardo">
+    <div class="item item0" data-ninja-turtle="leonardo">
       <span class="fruit">watermelon</span>
       <b>3.14</b>
       <i>42</i>
     </div>
+    <div class="item item2" data-ninja-turtle="raphael">
+      <span class="fruit">papaya</span>
+      <b>2.13</b>
+      <i>1001</i>
+    </div>
   </div>
 
   <h2>Filtering</h2>
diff --git a/test/sort-data.js b/test/sort-data.js
new file mode 100644
index 0000000..1e28cdc
--- /dev/null
+++ b/test/sort-data.js
@@ -0,0 +1,101 @@
+test( 'sort data', function() {
+
+  'use strict';
+
+  var iso = new Isotope( '#get-sort-data', {
+    layoutMode: 'fitRows',
+    getSortData: {
+      ninjaTurtle: '[data-ninja-turtle]',
+      fruit: 'span.fruit',
+      b: 'b parseFloat',
+      i: 'i parseInt',
+      bbroke: 'b foobar'
+    }
+  });
+
+  var item0 = iso.items[0];
+  var item1 = iso.items[1];
+
+  equal( item0.sortData.ninjaTurtle, 'leonardo', '[data-attr] shorthand' );
+  equal( item0.sortData.fruit, 'watermelon', 'query selector shorthand' );
+  equal( item0.sortData.b, 3.14, 'parseFloat parser' );
+  equal( item0.sortData.i, 42, 'parseInt parser' );
+  equal( item0.sortData.bbroke, '3.14', 'default nonparser' );
+
+  // -----  ----- //
+
+  var docElem = document.documentElement;
+  var textSetter = docElem.textContent !== undefined ? 'textContent' : 'innerText';
+
+  function setText( elem, value ) {
+    elem[ textSetter ] = value;
+  }
+
+  var elem0 = iso.items[0].element;
+  var elem1 = iso.items[1].element;
+
+  elem0.setAttribute( 'data-ninja-turtle', 'donatello' );
+  setText( elem0.querySelector('span.fruit'), 'mango' );
+  setText( elem0.querySelector('b'), '7.24' );
+  setText( elem0.querySelector('i'), 'foo' );
+
+  iso.updateSortData( elem0 );
+
+  var message = ', after updateSortData on single item'
+  equal( item0.sortData.ninjaTurtle, 'donatello', '[data-attr] shorthand' + message );
+  equal( item0.sortData.fruit, 'mango', 'query selector shorthand' + message );
+  equal( item0.sortData.b, 7.24, 'parseFloat parser' + message );
+  ok( isNaN( item0.sortData.i ), 'parseInt parser' + message );
+  equal( item0.sortData.bbroke, '7.24', 'default nonparser' + message );
+
+  // ----- update all items ----- //
+
+  elem0.setAttribute( 'data-ninja-turtle', 'leonardo' );
+  setText( elem0.querySelector('span.fruit'), 'passion fruit' );
+
+  elem1.setAttribute( 'data-ninja-turtle', 'michelangelo' );
+  setText( elem1.querySelector('span.fruit'), 'starfruit' );
+
+  // update all
+  iso.updateSortData();
+
+  message = ', after updateSortData on all items'
+  equal( item0.sortData.ninjaTurtle, 'leonardo', '[data-attr] shorthand' + message );
+  equal( item0.sortData.fruit, 'passion fruit', 'query selector shorthand' + message );
+  equal( item1.sortData.ninjaTurtle, 'michelangelo', '[data-attr] shorthand' + message );
+  equal( item1.sortData.fruit, 'starfruit', 'query selector shorthand' + message );
+
+  // ----- no items ----- //
+
+  iso.options.itemSelector = 'none';
+  iso.reloadItems();
+
+  iso.updateSortData();
+  ok( true, 'updateSortData on empty container is ok' );
+
+  iso.updateSortData( document.createElement('div') );
+  ok( true, 'updateSortData with non-item is ok, with no child items' );
+
+  iso.updateSortData( false );
+  ok( true, 'updateSortData with falsy is ok, with no child items' );
+
+  iso.updateSortData( [] );
+  ok( true, 'updateSortData with empty array is ok, with no child items' );
+
+  iso.updateSortData( jQuery() );
+  ok( true, 'updateSortData with empty jQuery object is ok, with no child items' );
+
+  // ----- bad getSortData ----- //
+
+  delete iso.options.itemSelector;
+  iso.options.getSortData.badQuery = 'bad-query';
+  iso.options.getSortData.badAttr = '[bad-attr]';
+  iso._getSorters();
+  iso.reloadItems();
+
+  item0 = iso.items[0];
+
+  equal( item0.sortData.badQuery, null, 'bad query returns null' );
+  equal( item0.sortData.badAttr, null, 'bad attr returns null' );
+
+});