diff --git a/main/ble.c b/main/ble.c
index 9a8e8e8..2ba6a86 100644
--- a/main/ble.c
+++ b/main/ble.c
@@ -138,8 +138,7 @@ static const struct ble_gatt_svc_def service_defs[] = {
   { 0 } // no more services
 };
 
-static int gatt_svr_chr_write(struct os_mbuf *om, uint16_t min_len, uint16_t max_len,
-    void *dst, uint16_t *len) {
+static int gatt_svr_chr_write(struct os_mbuf *om, uint16_t min_len, uint16_t max_len, void *dst, uint16_t *len) {
   uint16_t om_len;
   int rc;
 
@@ -159,6 +158,7 @@ static int gatt_svr_chr_write(struct os_mbuf *om, uint16_t min_len, uint16_t max
 static int svc_access_system(uint16_t conn_handle, uint16_t attr_handle, struct ble_gatt_access_ctxt *ctxt, void *arg) {
   uint16_t uuid16 = ble_uuid_u16(ctxt->chr->uuid);
   uint8_t value = 0;
+  uint16_t vlen = 0;
 
   ESP_LOGI(TAG, "0x%02X access: %d", uuid16, ctxt->op);
 
@@ -168,9 +168,11 @@ static int svc_access_system(uint16_t conn_handle, uint16_t attr_handle, struct
         ctxt->om,
         sizeof value,
         sizeof value,
-        &value, NULL
+        &value, &vlen
         );
 
+    ESP_LOGI(TAG, "value (%d): %d", vlen, value);
+
     switch(uuid16) {
       case BAROS_CHAR_POUR:
         if(value == 1) {