--- a/dom/media/tests/mochitest/dataChannel.js
+++ b/dom/media/tests/mochitest/dataChannel.js
@@ -185,17 +185,17 @@ var commandsCheckDataChannel = [
       is(channels.indexOf(result.channel), channels.length - 1, "Last channel used");
       is(result.data, message, "Received message has the correct content.");
     });
   }
 ];
 
 var commandsCheckLargeXfer = [
   function SEND_BIG_BUFFER(test) {
-    var size = 512*1024; // SCTP internal buffer is 256K, so we'll have ~256K queued
+    var size = 2*1024*1024; // SCTP internal buffer is 256K, so we'll have ~256K queued
     var buffer = new ArrayBuffer(size);
     // note: type received is always blob for binary data
     var options = {};
     options.bufferedAmountLowThreshold = 64*1024;
     info("Sending arraybuffer");
     return test.send(buffer, options).then(result => {
       ok(result.data instanceof Blob, "Received data is of instance Blob");
       is(result.data.size, size, "Received data has the correct size.");