--- a/testing/web-platform/tests/webvtt/webvtt-api-for-browsers/vttcue-interface/align.html
+++ b/testing/web-platform/tests/webvtt/webvtt-api-for-browsers/vttcue-interface/align.html
@@ -3,25 +3,25 @@
 <script src=/resources/testharness.js></script>
 <script src=/resources/testharnessreport.js></script>
 <div id=log></div>
 <script>
 test(function(){
     var video = document.createElement('video');
     document.body.appendChild(video);
     var c1 = new VTTCue(0, 1, 'text1');
-    assert_equals(c1.align, 'middle');
+    assert_equals(c1.align, 'center');
     var track = document.createElement('track');
     var t = track.track;
     t.addCue(c1);
-    assert_equals(c1.align, 'middle');
+    assert_equals(c1.align, 'center');
     video.appendChild(track);
-    assert_equals(c1.align, 'middle');
+    assert_equals(c1.align, 'center');
     t.mode = 'showing';
-    assert_equals(c1.align, 'middle');
+    assert_equals(c1.align, 'center');
     c1.align = 'start';
     assert_equals(c1.align, 'start');
     c1.align = 'end';
     assert_equals(c1.align, 'end');
     c1.align = 'start\u0000';
     assert_equals(c1.align, 'end');
 }, document.title+', script-created cue');
 
@@ -30,25 +30,25 @@ t_parsed.step(function(){
     var video = document.createElement('video');
     document.body.appendChild(video);
     var t = document.createElement('track');
     t.onload = this.step_func(function(){
         var c1 = t.track.cues[0];
         var c2 = t.track.cues[1];
         var c3 = t.track.cues[2];
         var c4 = t.track.cues[3];
-        assert_equals(c1.align, 'middle');
+        assert_equals(c1.align, 'center');
         assert_equals(c2.align, 'start');
-        assert_equals(c3.align, 'middle');
+        assert_equals(c3.align, 'center');
         assert_equals(c4.align, 'end');
         this.done();
     });
     t.onerror = this.step_func(function() {
       assert_unreached('got error event');
     });
     t.src = 'data:text/vtt,'+encodeURIComponent('WEBVTT\n\n00:00:00.000 --> 00:00:00.001\ntest\n\n'+
                                                 '00:00:00.000 --> 00:00:00.001 align:start\ntest\n\n'+
-                                                '00:00:00.000 --> 00:00:00.001 align:middle\ntest\n\n'+
+                                                '00:00:00.000 --> 00:00:00.001 align:center\ntest\n\n'+
                                                 '00:00:00.000 --> 00:00:00.001 align:end\ntest');
     t.track.mode = 'showing';
     video.appendChild(t);
 });
 </script>

--- a/testing/web-platform/tests/webvtt/webvtt-file-format-parsing/webvtt-file-parsing/001.html
+++ b/testing/web-platform/tests/webvtt/webvtt-file-format-parsing/webvtt-file-parsing/001.html
@@ -12,17 +12,17 @@ var cueDefaults = {
 "startTime":0,
 "endTime":1,
 "pauseOnExit":false,
 //"vertical":"", (not supported)
 "snapToLines":true,
 "line":-1,
 "position":50,
 "size":100,
-"align":"middle"
+"align":"center"
 }
 var cueCounts;
 (function(){
     var xhr = new XMLHttpRequest();
     xhr.open('GET', path+'cue-counts.json', true);
     xhr.onreadystatechange = function() {
         if (xhr.readyState == 4) {
             cueCounts = JSON.parse(xhr.responseText);

--- a/testing/web-platform/tests/webvtt/webvtt-file-format-parsing/webvtt-file-parsing/support/settings-multiple.vtt
+++ b/testing/web-platform/tests/webvtt/webvtt-file-format-parsing/webvtt-file-parsing/support/settings-multiple.vtt
@@ -3,14 +3,14 @@ WEBVTT
 00:00:00.000 --> 00:00:01.000 align:start line:1% vertical:lr size:50% position:25%
 {"align":"start",
 "line":1,
 "snapToLines":false,
 "vertical":"lr",
 "size":50,
 "position":25}
 
-00:00:00.000 --> 00:00:01.000 align:middle line:1 vertical:rl size:0% position:100%
-{"align":"middle",
+00:00:00.000 --> 00:00:01.000 align:center line:1 vertical:rl size:0% position:100%
+{"align":"center",
 "line":1,
 "vertical":"rl",
 "size":0,
 "position":100}
\ No newline at end of file