diff --git a/src/gba/gba-audio.c b/src/gba/gba-audio.c
index 1268ba1fa..3fe333a60 100644
--- a/src/gba/gba-audio.c
+++ b/src/gba/gba-audio.c
@@ -19,6 +19,8 @@ void GBAAudioInit(struct GBAAudio* audio) {
 	CircleBufferInit(&audio->right, GBA_AUDIO_SAMPLES * sizeof(int32_t));
 	CircleBufferInit(&audio->chA.fifo, GBA_AUDIO_FIFO_SIZE);
 	CircleBufferInit(&audio->chB.fifo, GBA_AUDIO_FIFO_SIZE);
+
+	pthread_mutex_init(&audio->bufferMutex, 0);
 }
 
 void GBAAudioDeinit(struct GBAAudio* audio) {
@@ -26,6 +28,8 @@ void GBAAudioDeinit(struct GBAAudio* audio) {
 	CircleBufferDeinit(&audio->right);
 	CircleBufferDeinit(&audio->chA.fifo);
 	CircleBufferDeinit(&audio->chB.fifo);
+
+	pthread_mutex_destroy(&audio->bufferMutex);
 }
 
 int32_t GBAAudioProcessEvents(struct GBAAudio* audio, int32_t cycles) {
@@ -171,6 +175,8 @@ static void _sample(struct GBAAudio* audio) {
 		sampleRight += audio->chB.sample;
 	}
 
+	pthread_mutex_lock(&audio->bufferMutex);
 	CircleBufferWrite32(&audio->left, sampleLeft);
 	CircleBufferWrite32(&audio->right, sampleRight);
+	pthread_mutex_unlock(&audio->bufferMutex);
 }
diff --git a/src/gba/gba-audio.h b/src/gba/gba-audio.h
index 536cf633e..56ead46d4 100644
--- a/src/gba/gba-audio.h
+++ b/src/gba/gba-audio.h
@@ -3,6 +3,7 @@
 
 #include "circle-buffer.h"
 
+#include <pthread.h>
 #include <stdint.h>
 
 struct GBADMA;
@@ -175,6 +176,8 @@ struct GBAAudio {
 	int32_t nextSample;
 
 	int32_t sampleInterval;
+
+	pthread_mutex_t bufferMutex;
 };
 
 void GBAAudioInit(struct GBAAudio* audio);
diff --git a/src/sdl/sdl-audio.c b/src/sdl/sdl-audio.c
index f6ae71bee..7e9cf83a2 100644
--- a/src/sdl/sdl-audio.c
+++ b/src/sdl/sdl-audio.c
@@ -13,7 +13,7 @@ int GBASDLInitAudio(struct GBASDLAudio* context) {
 	context->desiredSpec.freq = 44100;
 	context->desiredSpec.format = AUDIO_S16SYS;
 	context->desiredSpec.channels = 2;
-	context->desiredSpec.samples = GBA_AUDIO_SAMPLES >> 1;
+	context->desiredSpec.samples = GBA_AUDIO_SAMPLES >> 2;
 	context->desiredSpec.callback = _GBASDLAudioCallback;
 	context->desiredSpec.userdata = context;
 	context->audio = 0;
@@ -58,6 +58,7 @@ static void _GBASDLAudioCallback(void* context, Uint8* data, int len) {
 	struct StereoSample* ssamples = (struct StereoSample*) data;
 	len /= 2 * audioContext->obtainedSpec.channels;
 	if (audioContext->obtainedSpec.channels == 2) {
+		pthread_mutex_lock(&audioContext->audio->bufferMutex);
 		for (i = 0; i < len; ++i) {
 			audioContext->drift += audioContext->audio->sampleRate / (float) audioContext->obtainedSpec.freq;
 			while (audioContext->drift >= 0) {
@@ -66,5 +67,6 @@ static void _GBASDLAudioCallback(void* context, Uint8* data, int len) {
 			}
 			ssamples[i] = audioContext->currentSample;
 		}
+		pthread_mutex_unlock(&audioContext->audio->bufferMutex);
 	}
 }