diff --git a/src/libguac/audio.c b/src/libguac/audio.c
index da9ea487..fb8bcd3c 100644
--- a/src/libguac/audio.c
+++ b/src/libguac/audio.c
@@ -153,7 +153,7 @@ void guac_audio_stream_free(guac_audio_stream* audio) {
 }
 
 void guac_audio_stream_write_pcm(guac_audio_stream* audio, 
-        unsigned char* data, int length) {
+        const unsigned char* data, int length) {
 
     /* Update counter */
     audio->pcm_bytes_written += length;
@@ -194,7 +194,7 @@ void guac_audio_stream_flush(guac_audio_stream* audio) {
 }
 
 void guac_audio_stream_write_encoded(guac_audio_stream* audio,
-        unsigned char* data, int length) {
+        const unsigned char* data, int length) {
 
     /* Resize audio buffer if necessary */
     if (audio->encoded_data_used + length > audio->encoded_data_length) {
diff --git a/src/libguac/guacamole/audio.h b/src/libguac/guacamole/audio.h
index 898f543e..a243fa59 100644
--- a/src/libguac/guacamole/audio.h
+++ b/src/libguac/guacamole/audio.h
@@ -63,7 +63,7 @@ typedef void guac_audio_encoder_end_handler(guac_audio_stream* audio);
  * Handler which is called when the audio stream is flushed.
  */
 typedef void guac_audio_encoder_write_handler(guac_audio_stream* audio,
-        unsigned char* pcm_data, int length);
+        const unsigned char* pcm_data, int length);
 
 /**
  * Arbitrary audio codec encoder.
@@ -231,7 +231,7 @@ void guac_audio_stream_end(guac_audio_stream* stream);
  * @param length The number of bytes of PCM data provided.
  */
 void guac_audio_stream_write_pcm(guac_audio_stream* stream,
-        unsigned char* data, int length);
+        const unsigned char* data, int length);
 
 /**
  * Flushes the given audio stream.
@@ -251,7 +251,7 @@ void guac_audio_stream_flush(guac_audio_stream* stream);
  * @param length The number of bytes of data provided.
  */
 void guac_audio_stream_write_encoded(guac_audio_stream* audio,
-        unsigned char* data, int length);
+        const unsigned char* data, int length);
 
 #endif
 
diff --git a/src/libguac/ogg_encoder.c b/src/libguac/ogg_encoder.c
index 25abd7bf..e76b64e4 100644
--- a/src/libguac/ogg_encoder.c
+++ b/src/libguac/ogg_encoder.c
@@ -164,7 +164,7 @@ void ogg_encoder_end_handler(guac_audio_stream* audio) {
 }
 
 void ogg_encoder_write_handler(guac_audio_stream* audio, 
-        unsigned char* pcm_data, int length) {
+        const unsigned char* pcm_data, int length) {
 
     /* Get state */
     ogg_encoder_state* state = (ogg_encoder_state*) audio->data;
diff --git a/src/libguac/wav_encoder.c b/src/libguac/wav_encoder.c
index 23c9f110..fb7e40e4 100644
--- a/src/libguac/wav_encoder.c
+++ b/src/libguac/wav_encoder.c
@@ -167,7 +167,7 @@ void wav_encoder_end_handler(guac_audio_stream* audio) {
 }
 
 void wav_encoder_write_handler(guac_audio_stream* audio, 
-        unsigned char* pcm_data, int length) {
+        const unsigned char* pcm_data, int length) {
 
     /* Get state */
     wav_encoder_state* state = (wav_encoder_state*) audio->data;