--- a/master/master.c	Sat May 31 17:21:53 2014 +1200
+++ b/master/master.c	Sat May 31 18:08:27 2014 +1200
@@ -2849,7 +2849,7 @@
 /*****************************************************************************/
 
 int ecrt_master_sdo_download(ec_master_t *master, uint16_t slave_position,
-        uint16_t index, uint8_t subindex, uint8_t *data,
+        uint16_t index, uint8_t subindex, const uint8_t *data,
         size_t data_size, uint32_t *abort_code)
 {
     ec_sdo_request_t request;
@@ -2933,7 +2933,7 @@
 /*****************************************************************************/
 
 int ecrt_master_sdo_download_complete(ec_master_t *master,
-        uint16_t slave_position, uint16_t index, uint8_t *data,
+        uint16_t slave_position, uint16_t index, const uint8_t *data,
         size_t data_size, uint32_t *abort_code)
 {
     ec_sdo_request_t request;