--- a/dom/media/webvtt/vtt.jsm
+++ b/dom/media/webvtt/vtt.jsm
@@ -226,23 +226,17 @@ this.EXPORTED_SYMBOLS = ["WebVTT"];
       // Apply default values for any missing fields.
       cue.region = settings.get("region", null);
       cue.vertical = settings.get("vertical", "");
       cue.line = settings.get("line", "auto");
       cue.lineAlign = settings.get("lineAlign", "start");
       cue.snapToLines = settings.get("snapToLines", true);
       cue.size = settings.get("size", 100);
       cue.align = settings.get("align", "center");
-      cue.position = settings.get("position", {
-        start: 0,
-        left: 0,
-        middle: 50,
-        end: 100,
-        right: 100
-      }, cue.align);
+      cue.position = settings.get("position", "auto");
       cue.positionAlign = settings.get("positionAlign", "center");
     }
 
     function skipWhitespace() {
       input = input.replace(/^\s+/, "");
     }
 
     // 4.1 WebVTT cue timings.