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;
                 }
             }
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 2f65370..7d583bb5 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -910,11 +910,11 @@
         goto Exit;
     }
 
-    // Reject any effect on multichannel sinks.
+    // Reject any effect on mixer or duplicating multichannel sinks.
     // TODO: fix both format and multichannel issues with effects.
-    if (mChannelCount != FCC_2) {
-        ALOGW("createEffect_l() Cannot add effect %s for multichannel(%d) thread",
-                desc->name, mChannelCount);
+    if ((mType == MIXER || mType == DUPLICATING) && mChannelCount != FCC_2) {
+        ALOGW("createEffect_l() Cannot add effect %s for multichannel(%d) %s threads",
+                desc->name, mChannelCount, mType == MIXER ? "MIXER" : "DUPLICATING");
         lStatus = BAD_VALUE;
         goto Exit;
     }