diff --git a/services/audioflinger/AudioMixer.h b/services/audioflinger/AudioMixer.h
index 3b972bb..f4f142b 100644
--- a/services/audioflinger/AudioMixer.h
+++ b/services/audioflinger/AudioMixer.h
@@ -21,15 +21,15 @@
 #include <stdint.h>
 #include <sys/types.h>
 
+#include <hardware/audio_effect.h>
+#include <media/AudioBufferProvider.h>
+#include <media/nbaio/NBLog.h>
+#include <system/audio.h>
+#include <utils/Compat.h>
 #include <utils/threads.h>
 
-#include <media/AudioBufferProvider.h>
 #include "AudioResampler.h"
 
-#include <hardware/audio_effect.h>
-#include <system/audio.h>
-#include <media/nbaio/NBLog.h>
-
 // FIXME This is actually unity gain, which might not be max in future, expressed in U.12
 #define MAX_GAIN_INT AudioMixer::UNITY_GAIN_INT
 
@@ -58,7 +58,7 @@
     static const uint32_t MAX_NUM_CHANNELS_TO_DOWNMIX = AUDIO_CHANNEL_COUNT_MAX;
 
     static const uint16_t UNITY_GAIN_INT = 0x1000;
-    static const float    UNITY_GAIN_FLOAT = 1.0f;
+    static const CONSTEXPR float UNITY_GAIN_FLOAT = 1.0f;
 
     enum { // names