diff --git a/src/audio/google/google_rtc_audio_processing_mock.c b/src/audio/google/google_rtc_audio_processing_mock.c
index 6073e125a539..fe219d36e695 100644
--- a/src/audio/google/google_rtc_audio_processing_mock.c
+++ b/src/audio/google/google_rtc_audio_processing_mock.c
@@ -10,6 +10,8 @@
 #include <string.h>
 #include <stdint.h>
 
+#include <sof/audio/format.h>
+#include <sof/math/numbers.h>
 #include <rtos/alloc.h>
 #include "ipc/topology.h"
 
@@ -145,11 +147,17 @@ int GoogleRtcAudioProcessingProcessCapture_int16(GoogleRtcAudioProcessingState *
 	int16_t *ref = state->aec_reference;
 	int16_t *mic = (int16_t *) src;
 	int16_t *out = dest;
-	int n;
+	int channels;
+	int n, m;
+
+	channels = MIN(state->num_capture_channels, state->num_aec_reference_channels);
+	channels = MIN(state->num_output_channels, channels);
 
 	memset(dest, 0, sizeof(int16_t) * state->num_output_channels * state->num_frames);
 	for (n = 0; n < state->num_frames; ++n) {
-		*out = *mic + *ref;
+		for (m = 0; m < channels; m++)
+			out[m] = sat_int16((int32_t)mic[m] + ref[m]);
+
 		ref += state->num_aec_reference_channels;
 		out += state->num_output_channels;
 		mic += state->num_capture_channels;