diff --git a/src/zm_camera.h b/src/zm_camera.h
index 4163b761a..2996b9a2a 100644
--- a/src/zm_camera.h
+++ b/src/zm_camera.h
@@ -110,10 +110,10 @@ public:
     //return (type == FFMPEG_SRC )||(type == REMOTE_SRC);
   }
 
-  virtual AVStream      *get_VideoStream() { return NULL; };
-  virtual AVStream      *get_AudioStream() { return NULL; };
-  virtual AVCodecContext     *get_VideoCodecContext() { return NULL; };
-  virtual AVCodecContext     *get_AudioCodecContext() { return NULL; };
+  virtual AVStream      *get_VideoStream() { return nullptr; };
+  virtual AVStream      *get_AudioStream() { return nullptr; };
+  virtual AVCodecContext     *get_VideoCodecContext() { return nullptr; };
+  virtual AVCodecContext     *get_AudioCodecContext() { return nullptr; };
   int            get_VideoStreamId() { return mVideoStreamId; };
   int            get_AudioStreamId() { return mAudioStreamId; };