--- a/dom/media/webvtt/vtt.jsm
+++ b/dom/media/webvtt/vtt.jsm
@@ -172,17 +172,17 @@ this.EXPORTED_SYMBOLS = ["WebVTT"];
     // 4.1 WebVTT timestamp
     function consumeTimeStamp() {
       var ts = collectTimeStamp(input);
       if (ts === null) {
         throw new ParsingError(ParsingError.Errors.BadTimeStamp,
                               "Malformed timestamp: " + oInput);
       }
       // Remove time stamp from input.
-      input = input.replace(/^[^\sa-zA-Z-]+/, "");
+      input = input.replace(/^[^\s\uFFFDa-zA-Z-]+/, "");
       return ts;
     }
 
     // 4.4.2 WebVTT cue settings
     function consumeCueSettings(input, cue) {
       var settings = new Settings();
 
       parseOptions(input, function (k, v) {
@@ -1261,17 +1261,18 @@ this.EXPORTED_SYMBOLS = ["WebVTT"];
         // Advance the buffer early in case we fail below.
         if (buffer[pos] === '\r') {
           ++pos;
         }
         if (buffer[pos] === '\n') {
           ++pos;
         }
         self.buffer = buffer.substr(pos);
-        return line;
+        // Spec defined replacement.
+        return line.replace(/[\u0000]/g, "\uFFFD");
       }
 
       function createCueIfNeeded() {
         if (!self.cue) {
           self.cue = new self.window.VTTCue(0, 0, "");
         }
       }
 

deleted file mode 100644
--- a/testing/web-platform/meta/webvtt/webvtt-file-format-parsing/webvtt-file-parsing/001.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[001.html]
-  type: testharness
-  [WebVTT parser tests, nulls.vtt]
-    expected: FAIL
\ No newline at end of file