diff --git a/include/media/ToneGenerator.h b/include/media/ToneGenerator.h
index 98c4332..8406ed6 100644
--- a/include/media/ToneGenerator.h
+++ b/include/media/ToneGenerator.h
@@ -17,11 +17,12 @@
 #ifndef ANDROID_TONEGENERATOR_H_
 #define ANDROID_TONEGENERATOR_H_
 
-#include <utils/RefBase.h>
-#include <utils/KeyedVector.h>
-#include <utils/threads.h>
 #include <media/AudioSystem.h>
 #include <media/AudioTrack.h>
+#include <utils/Compat.h>
+#include <utils/KeyedVector.h>
+#include <utils/RefBase.h>
+#include <utils/threads.h>
 
 namespace android {
 
@@ -207,7 +208,7 @@
     static const unsigned int TONEGEN_MAX_WAVES = 3;     // Maximun number of sine waves in a tone segment
     static const unsigned int TONEGEN_MAX_SEGMENTS = 12;  // Maximun number of segments in a tone descriptor
     static const unsigned int TONEGEN_INF = 0xFFFFFFFF;  // Represents infinite time duration
-    static const float TONEGEN_GAIN = 0.9;  // Default gain passed to  WaveGenerator().
+    static const CONSTEXPR float TONEGEN_GAIN = 0.9;  // Default gain passed to  WaveGenerator().
 
     // ToneDescriptor class contains all parameters needed to generate a tone:
     //    - The array waveFreq[]: