diff --git a/AV.cc b/AV.cc
index 6acd312..ea0aeef 100644
--- a/AV.cc
+++ b/AV.cc
@@ -5,6 +5,7 @@
 #include <SDL_sound.h>
 #include <math.h>
 #include <limits.h>                 /* INT_MAX */
+#include <stdint.h>
 
 #include <iostream>
 
@@ -60,6 +61,7 @@ AV::AV()
         cerr << "SDL_OpenAudio() error." << endl;
         exit(3);
     }
+    m_sound_buffer = new int16_t[CALLBACK_SAMPLES * CHANNELS];
 
     m_active_sounds_mutex = SDL_CreateMutex();
 }
@@ -71,6 +73,7 @@ AV::~AV()
     SDL_CloseAudio();
     Sound_Quit();
     SDL_Quit();
+    delete[] m_sound_buffer;
 }
 
 void AV::start(int width, int height, bool fullscreen, bool grab_input,
@@ -159,14 +162,29 @@ void AV::playCallback(Uint8 * stream, int len)
 {
     memset(stream, 0, len);
     SDL_mutexP(m_active_sounds_mutex);
+    if (len > CALLBACK_SAMPLES * CHANNELS * BYTES_PER_SAMPLE)
+    {
+        cerr << "anaglym bug: callback buffer length = " << len
+            << ", sound buffer size = "
+            << CALLBACK_SAMPLES * CHANNELS * BYTES_PER_SAMPLE << endl;
+        exit(38);
+    }
+    memset(stream, 0, len);
     for (std::set<Sound *>::iterator it = m_active_sounds.begin();
          it != m_active_sounds.end();
          it++)
     {
-        if ((*it)->decode(stream, len) == 0)
+        int bytes_decoded = (*it)->decode((Uint8 *)m_sound_buffer, len);
+        if (bytes_decoded == 0)
         {
             m_active_sounds.erase(it);
         }
+        for (int i = 0, samples_decoded = bytes_decoded / 2;
+             i < samples_decoded;
+             i++)
+        {
+            stream[i] = min(INT_MAX, stream[i] + m_sound_buffer[i]);
+        }
     }
     if (m_active_sounds.size() == 0)
     {
diff --git a/AV.h b/AV.h
index 2e9e73a..da50ba5 100644
--- a/AV.h
+++ b/AV.h
@@ -4,6 +4,7 @@
 
 #include <SDL.h>
 #include <SDL_sound.h>
+#include <stdint.h>
 
 #include <set>
 
@@ -83,6 +84,7 @@ class AV
 #endif
         std::set< Sound * > m_active_sounds;
         SDL_mutex * m_active_sounds_mutex;
+        int16_t * m_sound_buffer;
 };
 
 #endif