--- a/testing/web-platform/meta/webvtt/interfaces.html.ini
+++ b/testing/web-platform/meta/webvtt/interfaces.html.ini
@@ -13,16 +13,19 @@
     expected: FAIL
 
   [VTTCue interface: new VTTCue(0, 1, "foo") must inherit property "region" with the proper type (0)]
     expected: FAIL
 
   [VTTCue interface: new VTTCue(0, 1, "foo") must inherit property "line" with the proper type (3)]
     expected: FAIL
 
+  [VTTCue interface: new VTTCue(0, 1, "foo") must inherit property "position" with the proper type (5)]
+    expected: FAIL
+
   [VTTRegion interface: existence and properties of interface object]
     expected: FAIL
 
   [VTTRegion interface object length]
     expected: FAIL
 
   [VTTRegion interface: existence and properties of interface prototype object]
     expected: FAIL

--- a/testing/web-platform/tests/webvtt/interfaces.html
+++ b/testing/web-platform/tests/webvtt/interfaces.html
@@ -14,17 +14,17 @@ enum DirectionSetting { "" /* horizontal
 enum AlignSetting { "start", "middle", "end", "left", "right" };
 [Constructor(double startTime, double endTime, DOMString text)]
 interface VTTCue : TextTrackCue {
            attribute VTTRegion? region;
            attribute DirectionSetting vertical;
            attribute boolean snapToLines;
            attribute (double or AutoKeyword) line;
            attribute AlignSetting lineAlign;
-           attribute double position;
+           attribute (double or AutoKeyword) position;
            attribute AlignSetting positionAlign;
            attribute double size;
            attribute AlignSetting align;
            attribute DOMString text;
   DocumentFragment getCueAsHTML();
 };
 
 enum ScrollSetting { "" /* none */, "up" };