diff --git a/audio/audio.h b/audio/audio.h
index f27a12298f..b883ebfb1f 100644
--- a/audio/audio.h
+++ b/audio/audio.h
@@ -60,7 +60,7 @@ typedef enum {
 
 struct audio_capture_ops {
     void (*notify) (void *opaque, audcnotification_e cmd);
-    void (*capture) (void *opaque, void *buf, int size);
+    void (*capture) (void *opaque, const void *buf, int size);
     void (*destroy) (void *opaque);
 };
 
diff --git a/audio/wavcapture.c b/audio/wavcapture.c
index 8d7ce2eda1..17e87ed6f4 100644
--- a/audio/wavcapture.c
+++ b/audio/wavcapture.c
@@ -71,7 +71,7 @@ static void wav_destroy (void *opaque)
     g_free (wav->path);
 }
 
-static void wav_capture (void *opaque, void *buf, int size)
+static void wav_capture(void *opaque, const void *buf, int size)
 {
     WAVState *wav = opaque;
 
diff --git a/ui/vnc.c b/ui/vnc.c
index 1d7138a3a0..12a12714e1 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -1177,7 +1177,7 @@ static void audio_capture_destroy(void *opaque)
 {
 }
 
-static void audio_capture(void *opaque, void *buf, int size)
+static void audio_capture(void *opaque, const void *buf, int size)
 {
     VncState *vs = opaque;