diff --git a/include/media/AudioEffect.h b/include/media/AudioEffect.h
index 1417416..7b0b443 100644
--- a/include/media/AudioEffect.h
+++ b/include/media/AudioEffect.h
@@ -226,8 +226,8 @@
     AudioEffect(const effect_uuid_t *type,
                 const effect_uuid_t *uuid = NULL,
                   int32_t priority = 0,
-                  effect_callback_t cbf = 0,
-                  void* user = 0,
+                  effect_callback_t cbf = NULL,
+                  void* user = NULL,
                   int sessionId = 0,
                   audio_io_handle_t io = 0
                   );
@@ -238,8 +238,8 @@
     AudioEffect(const char *typeStr,
                     const char *uuidStr = NULL,
                     int32_t priority = 0,
-                    effect_callback_t cbf = 0,
-                    void* user = 0,
+                    effect_callback_t cbf = NULL,
+                    void* user = NULL,
                     int sessionId = 0,
                     audio_io_handle_t io = 0
                     );
@@ -260,8 +260,8 @@
             status_t    set(const effect_uuid_t *type,
                             const effect_uuid_t *uuid = NULL,
                             int32_t priority = 0,
-                            effect_callback_t cbf = 0,
-                            void* user = 0,
+                            effect_callback_t cbf = NULL,
+                            void* user = NULL,
                             int sessionId = 0,
                             audio_io_handle_t io = 0
                             );
diff --git a/include/media/AudioRecord.h b/include/media/AudioRecord.h
index 76ec3b1..c8c5dba 100644
--- a/include/media/AudioRecord.h
+++ b/include/media/AudioRecord.h
@@ -155,8 +155,8 @@
                                     uint32_t channelMask = AUDIO_CHANNEL_IN_MONO,
                                     int frameCount      = 0,
                                     uint32_t flags      = 0,
-                                    callback_t cbf = 0,
-                                    void* user = 0,
+                                    callback_t cbf = NULL,
+                                    void* user = NULL,
                                     int notificationFrames = 0,
                                     int sessionId = 0);
 
@@ -181,8 +181,8 @@
                             uint32_t channelMask = AUDIO_CHANNEL_IN_MONO,
                             int frameCount      = 0,
                             uint32_t flags      = 0,
-                            callback_t cbf = 0,
-                            void* user = 0,
+                            callback_t cbf = NULL,
+                            void* user = NULL,
                             int notificationFrames = 0,
                             bool threadCanCallJava = false,
                             int sessionId = 0);
diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index 98abfbd..02c85cd 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -148,8 +148,8 @@
                                     int channelMask      = 0,
                                     int frameCount       = 0,
                                     uint32_t flags       = 0,
-                                    callback_t cbf       = 0,
-                                    void* user           = 0,
+                                    callback_t cbf       = NULL,
+                                    void* user           = NULL,
                                     int notificationFrames = 0,
                                     int sessionId = 0);
 
@@ -180,8 +180,8 @@
                                     int channelMask     = 0,
                                     const sp<IMemory>& sharedBuffer = 0,
                                     uint32_t flags      = 0,
-                                    callback_t cbf      = 0,
-                                    void* user          = 0,
+                                    callback_t cbf      = NULL,
+                                    void* user          = NULL,
                                     int notificationFrames = 0,
                                     int sessionId = 0);
 
@@ -204,8 +204,8 @@
                             int channelMask     = 0,
                             int frameCount      = 0,
                             uint32_t flags      = 0,
-                            callback_t cbf      = 0,
-                            void* user          = 0,
+                            callback_t cbf      = NULL,
+                            void* user          = NULL,
                             int notificationFrames = 0,
                             const sp<IMemory>& sharedBuffer = 0,
                             bool threadCanCallJava = false,
diff --git a/include/media/Visualizer.h b/include/media/Visualizer.h
index 1a4cbca..60fa15b 100644
--- a/include/media/Visualizer.h
+++ b/include/media/Visualizer.h
@@ -66,8 +66,8 @@
      * See AudioEffect constructor for details on parameters.
      */
                         Visualizer(int32_t priority = 0,
-                                   effect_callback_t cbf = 0,
-                                   void* user = 0,
+                                   effect_callback_t cbf = NULL,
+                                   void* user = NULL,
                                    int sessionId = 0);
 
                         ~Visualizer();