diff --git a/media/libmedia/AudioSystem.cpp b/media/libmedia/AudioSystem.cpp
index 9c2a8ba..1a3fcd6 100644
--- a/media/libmedia/AudioSystem.cpp
+++ b/media/libmedia/AudioSystem.cpp
@@ -835,6 +835,7 @@
 const char *AudioParameter::keyFormat = "format";
 const char *AudioParameter::keyChannels = "channels";
 const char *AudioParameter::keyFrameCount = "frame_count";
+const char *AudioParameter::keyInputSource = "input_source";
 
 AudioParameter::AudioParameter(const String8& keyValuePairs)
 {