diff --git a/modules/audio_processing/audio_processing_impl.cc b/modules/audio_processing/audio_processing_impl.cc
index 526d7d5974..ddea435e30 100644
--- a/modules/audio_processing/audio_processing_impl.cc
+++ b/modules/audio_processing/audio_processing_impl.cc
@@ -1866,9 +1866,8 @@ void AudioProcessingImpl::InitializePreAmplifier() {
 void AudioProcessingImpl::InitializeResidualEchoDetector() {
   RTC_DCHECK(private_submodules_->echo_detector);
   private_submodules_->echo_detector->Initialize(
-      proc_sample_rate_hz(), num_proc_channels(),
-      formats_.render_processing_format.sample_rate_hz(),
-      formats_.render_processing_format.num_channels());
+      proc_sample_rate_hz(), 1,
+      formats_.render_processing_format.sample_rate_hz(), 1);
 }
 
 void AudioProcessingImpl::InitializePostProcessor() {