diff --git a/nemu/src/device/audio.c b/nemu/src/device/audio.c
index 16cf7bf..64f5977 100644
--- a/nemu/src/device/audio.c
+++ b/nemu/src/device/audio.c
@@ -17,6 +17,8 @@
 #include <device/map.h>
 #include <SDL2/SDL.h>
 
+#include <stdatomic.h>
+
 enum {
   reg_freq,
   reg_channels,
@@ -30,13 +32,12 @@ enum {
 static uint8_t *sbuf = NULL;
 static uint32_t *audio_base = NULL;
 static uint32_t pos_read = 0;
-static uint32_t audio_count = 0;
+static atomic_char32_t audio_count = 0;
 
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 
 static void audio_callback(void *userdata, uint8_t *stream, int len) {
-  SDL_LockAudio();
-  uint32_t count = audio_count;
+  uint32_t count = atomic_load(&audio_count);
   uint32_t read_cnt = MIN(count, len);
   uint32_t to_end_cnt = CONFIG_SB_SIZE - pos_read;
   int32_t out_bound_cnt = read_cnt - to_end_cnt;
@@ -50,8 +51,8 @@ static void audio_callback(void *userdata, uint8_t *stream, int len) {
   pos_read += read_cnt;
   pos_read %= CONFIG_SB_SIZE;
   // if (len > read_cnt) memset(stream + read_cnt, 0, len - read_cnt);
-  audio_count -= read_cnt;
-  SDL_UnlockAudio();
+  count -= read_cnt;
+  atomic_store(&audio_count, count);
 }
 
 static inline void init_audio_dev() {
@@ -85,11 +86,9 @@ static void audio_io_handler(uint32_t offset, int len, bool is_write) {
       }
       break;
     case reg_count:
-      SDL_LockAudio();
       // TODO: must be add a lock here
-      if (is_write) audio_count = audio_base[reg_count];
-      else audio_base[reg_count] = audio_count;
-      SDL_UnlockAudio();
+      if (is_write) atomic_store(&audio_count, audio_base[reg_count]);
+      else audio_base[reg_count] = atomic_load(&audio_count);
       break;
     default:
       assert(0);