diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 7f0fc1f..9a0ba1a 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -3735,6 +3735,12 @@
 
         using namespace std::chrono_literals;
         auto inChannelMask = audio_channel_mask_out_to_in(track->channelMask());
+        if (inChannelMask == AUDIO_CHANNEL_INVALID) {
+            // The downstream PatchTrack has the proper output channel mask,
+            // so if there is no input channel mask equivalent, we can just
+            // use an index mask here to create the PatchRecord.
+            inChannelMask = audio_channel_mask_out_to_in_index_mask(track->channelMask());
+        }
         sp patchRecord = new RecordThread::PatchRecord(nullptr /* thread */,
                                                        track->sampleRate(),
                                                        inChannelMask,