diff --git a/src/ble/att_db.c b/src/ble/att_db.c
index e795cbf38..697269efc 100644
--- a/src/ble/att_db.c
+++ b/src/ble/att_db.c
@@ -1098,7 +1098,7 @@ static void handle_write_command(att_connection_t * att_connection, uint8_t * re
 // MARK: helper for ATT_HANDLE_VALUE_NOTIFICATION and ATT_HANDLE_VALUE_INDICATION
 static uint16_t prepare_handle_value(att_connection_t * att_connection,
                                      uint16_t handle,
-                                     uint8_t *value,
+                                     const uint8_t *value,
                                      uint16_t value_len, 
                                      uint8_t * response_buffer){
     little_endian_store_16(response_buffer, 1, handle);
@@ -1112,7 +1112,7 @@ static uint16_t prepare_handle_value(att_connection_t * att_connection,
 // MARK: ATT_HANDLE_VALUE_NOTIFICATION 0x1b
 uint16_t att_prepare_handle_value_notification(att_connection_t * att_connection,
                                                uint16_t handle,
-                                               uint8_t *value,
+                                               const uint8_t *value,
                                                uint16_t value_len, 
                                                uint8_t * response_buffer){
 
@@ -1123,7 +1123,7 @@ uint16_t att_prepare_handle_value_notification(att_connection_t * att_connection
 // MARK: ATT_HANDLE_VALUE_INDICATION 0x1d
 uint16_t att_prepare_handle_value_indication(att_connection_t * att_connection,
                                              uint16_t handle,
-                                             uint8_t *value,
+                                             const uint8_t *value,
                                              uint16_t value_len, 
                                              uint8_t * response_buffer){
 
diff --git a/src/ble/att_db.h b/src/ble/att_db.h
index ca3679b54..c318088eb 100644
--- a/src/ble/att_db.h
+++ b/src/ble/att_db.h
@@ -158,7 +158,7 @@ uint16_t att_handle_request(att_connection_t * att_connection,
  */
 uint16_t att_prepare_handle_value_notification(att_connection_t * att_connection,
                                                uint16_t attribute_handle,
-                                               uint8_t *value,
+                                               const uint8_t *value,
                                                uint16_t value_len, 
                                                uint8_t * response_buffer);
 
@@ -172,7 +172,7 @@ uint16_t att_prepare_handle_value_notification(att_connection_t * att_connection
  */
 uint16_t att_prepare_handle_value_indication(att_connection_t * att_connection,
                                              uint16_t attribute_handle,
-                                             uint8_t *value,
+                                             const uint8_t *value,
                                              uint16_t value_len, 
                                              uint8_t * response_buffer);
 
diff --git a/src/ble/att_server.c b/src/ble/att_server.c
index b436387a5..9c0b720bf 100644
--- a/src/ble/att_server.c
+++ b/src/ble/att_server.c
@@ -988,7 +988,7 @@ int att_server_request_to_send_indication(btstack_context_callback_registration_
     return ERROR_CODE_SUCCESS;
 }
 
-int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){
+int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len){
     att_server_t * att_server = att_server_for_handle(con_handle);
     if (!att_server) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
 
@@ -1000,7 +1000,7 @@ int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, ui
 	return l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size);
 }
 
-int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){
+int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len){
     att_server_t * att_server = att_server_for_handle(con_handle);
     if (!att_server) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
 
diff --git a/src/ble/att_server.h b/src/ble/att_server.h
index d6eedd3f6..0995a9d97 100644
--- a/src/ble/att_server.h
+++ b/src/ble/att_server.h
@@ -124,7 +124,7 @@ int att_server_request_to_send_indication(btstack_context_callback_registration_
  * @param value_len
  * @return 0 if ok, error otherwise
  */
-int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len);
+int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len);
 
 /*
  * @brief indicate value change to client. client is supposed to reply with an indication_response
@@ -134,7 +134,7 @@ int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, ui
  * @param value_len
  * @return 0 if ok, error otherwise
  */
-int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len);
+int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len);
 
 #ifdef ENABLE_ATT_DELAYED_RESPONSE
 /*