diff --git a/platform/esb/dev/sound-sensor.c b/platform/esb/dev/sound-sensor.c
index 3358d2ff5..76c1f4dec 100644
--- a/platform/esb/dev/sound-sensor.c
+++ b/platform/esb/dev/sound-sensor.c
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * @(#)$Id: sound-sensor.c,v 1.2 2008/04/25 15:55:37 joxe Exp $
+ * @(#)$Id: sound-sensor.c,v 1.3 2008/07/08 12:35:05 nifi Exp $
  */
 #include <stdlib.h>
 #include "contiki-esb.h"
@@ -153,7 +153,7 @@ configure(int type, void *c)
   } else if (type == SOUND_SET_BUFFER_SIZE) {
     buffer_size = (int) c;
   } else if (type == SOUND_SET_DIV) {
-    sample_div = (int8_t) c;
+    sample_div = (int) c & 0xff;
   } else if(type == SOUND_START_SAMPLE) {
     if(buffer_size > 0) {
       leds_on(LEDS_RED);