diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 31c5a1a..83e4ae1 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -340,7 +340,8 @@
             uint32_t channelCount = FCC_2; // stereo is default
             if (kEnableExtendedChannels) {
                 channelCount = audio_channel_count_from_out_mask(channelMask);
-                if (channelCount > AudioMixer::MAX_NUM_CHANNELS) {
+                if (channelCount < FCC_2 // mono is not supported at this time
+                        || channelCount > AudioMixer::MAX_NUM_CHANNELS) {
                     return false;
                 }
             }