diff --git a/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/automation-rate-testing.js b/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/automation-rate-testing.js
index 73892dd84588..43279f91d68d 100644
--- a/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/automation-rate-testing.js
+++ b/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/automation-rate-testing.js
@@ -45,7 +45,7 @@
 // The promise from |startRendering| is returned.
 function doTest(context, should, options) {
   let merger = new ChannelMergerNode(
-      context, {numberOfInputs: context.destination.numberOfChannels});
+      context, {numberOfInputs: context.destination.channelCount});
   merger.connect(context.destination);
 
   let src = null;
diff --git a/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/k-rate-oscillator.html b/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/k-rate-oscillator.html
index 1672f0d975f2..6803f55eab00 100644
--- a/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/k-rate-oscillator.html
+++ b/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/k-rate-oscillator.html
@@ -32,7 +32,7 @@
               });
 
               let merger = new ChannelMergerNode(
-                  context, {numberOfInputs: context.numberOfChannels});
+                  context, {numberOfInputs: context.destination.channelCount});
               merger.connect(context.destination);
               let inverter = new GainNode(context, {gain: -1});
               inverter.connect(merger, 0, 2);