diff --git a/code/b-parasite/Makefile b/code/b-parasite/Makefile
index a76db5b..062f041 100644
--- a/code/b-parasite/Makefile
+++ b/code/b-parasite/Makefile
@@ -217,7 +217,7 @@ CFLAGS += -DSOFTDEVICE_PRESENT
 CFLAGS += -DEBUG
 CFLAGS += -mcpu=cortex-m4
 CFLAGS += -mthumb -mabi=aapcs
-# CFLAGS += -Wall -Werror
+CFLAGS += -Wall -Werror
 CFLAGS += -mfloat-abi=hard -mfpu=fpv4-sp-d16
 # keep every function in a separate section, this allows linker to discard unused ones
 CFLAGS += -ffunction-sections -fdata-sections -fno-strict-aliasing
diff --git a/code/b-parasite/src/main.c b/code/b-parasite/src/main.c
index 546c0cc..56d6dae 100644
--- a/code/b-parasite/src/main.c
+++ b/code/b-parasite/src/main.c
@@ -34,7 +34,6 @@ void assert_nrf_callback(uint16_t line_num, const uint8_t *p_file_name) {
 static void log_init(void) {
   ret_code_t err_code = NRF_LOG_INIT(NULL);
   APP_ERROR_CHECK(err_code);
-
   NRF_LOG_DEFAULT_BACKENDS_INIT();
   NRF_LOG_INFO("Log inited");
 }
@@ -48,11 +47,6 @@ static void leds_init(void) {
   NRF_LOG_INFO("Leds inited");
 }
 
-static void timers_init(void) {
-  ret_code_t err_code = app_timer_init();
-  APP_ERROR_CHECK(err_code);
-}
-
 #define FPU_EXCEPTION_MASK 0x0000009F
 
 static void power_management_init(void) {
@@ -61,7 +55,6 @@ static void power_management_init(void) {
   APP_ERROR_CHECK(err_code);
 }
 
-//
 static void power_manage(void) {
   __set_FPSCR(__get_FPSCR() & ~(FPU_EXCEPTION_MASK));
   (void)__get_FPSCR();
@@ -69,10 +62,12 @@ static void power_manage(void) {
   nrf_pwr_mgmt_run();
 }
 
+static uint8_t data;
 static void rtc_callback() {
   NRF_LOG_INFO("rtc callback running...\n");
   NRF_LOG_FLUSH();
   nrf_gpio_pin_set(LED_PIN);
+  prst_ble_update_adv_data(++data);
   prst_adv_start();
   nrf_delay_ms(300);
   prst_adv_stop();
@@ -85,7 +80,6 @@ int main(void) {
   leds_init();
   power_management_init();
   prst_ble_init();
-  prst_ble_update_adv_data(1);
 
   prst_rtc_set_callback(rtc_callback);
   prst_rtc_init();
diff --git a/code/b-parasite/src/prst/ble.c b/code/b-parasite/src/prst/ble.c
index ec1dacd..eed18de 100644
--- a/code/b-parasite/src/prst/ble.c
+++ b/code/b-parasite/src/prst/ble.c
@@ -3,35 +3,53 @@
 #include <ble_advdata.h>
 #include <ble_gap.h>
 #include <nordic_common.h>
+#include <nrf_log.h>
 #include <nrf_sdh.h>
 #include <nrf_sdh_ble.h>
 
 #include "prst_config.h"
 
-// Environmental sensing.
+// We need to pick a service UUID for broadcasting our sensor data.
+// 0x181a is defined as "environmental sensing", which seems appopriate.
 #define SERVICE_UUID 0x181a
 
-#define NAME "Prst"
-
-#define SERVICE_DATA_LEN 8
-
 // The connection to configure. We only have the one.
 #define PRST_CONN_CFG_TAG 1
 
 #define NON_CONNECTABLE_ADV_INTERVAL MSEC_TO_UNITS(100, UNIT_0_625_MS)
 
+// Sensor data payload that will go into the advertisement message.
+#define SERVICE_DATA_LEN 8
 static uint8_t service_data[SERVICE_DATA_LEN];
 
 // Stores the encoded advertisement data. As per BLE spec, 31 bytes max.
 static uint8_t encoded_adv_data_[BLE_GAP_ADV_SET_DATA_SIZE_MAX];
 
 // Structure holding high level advertisement data and contains a pointer to
-// the actual advertised bytes.
-static ble_gap_adv_data_t adv_data_ = {
+// the actual encoded advertised bytes.
+static ble_gap_adv_data_t gap_adv_data_ = {
     .adv_data = {.p_data = encoded_adv_data_,
                  .len = BLE_GAP_ADV_SET_DATA_SIZE_MAX},
     .scan_rsp_data = {.p_data = NULL, .len = 0}};
 
+// We'll put our sensor data inside an advertisement service.
+static ble_advdata_service_data_t advdata_service_data_ = {
+    .service_uuid = SERVICE_UUID,
+    .data = {
+        .p_data = service_data,
+        .size = SERVICE_DATA_LEN,
+    }};
+
+// Holds the service data to be broadcasted. The contents of this struct
+// will be encoded into gap_adv_data.
+// Warning: do not update this while advertising.
+static ble_advdata_t adv_data_ = {
+    .name_type = BLE_ADVDATA_FULL_NAME,
+    .flags = BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED,
+    .p_service_data_array = &advdata_service_data_,
+    .service_data_count = 1,
+};
+
 // NRF supports multiple advertisement sets. This initialization is a request
 // for configuring a new one.
 static uint8_t adv_handle_ = BLE_GAP_ADV_SET_HANDLE_NOT_SET;
@@ -40,25 +58,8 @@ static uint8_t adv_handle_ = BLE_GAP_ADV_SET_HANDLE_NOT_SET;
 static ble_gap_adv_params_t adv_params_;
 
 static void init_advertisement_data() {
-  // Build advertisement data.
-  ble_advdata_t advdata;
-  memset(&advdata, 0, sizeof(advdata));
-  // memset(&adv_params_, 0, sizeof(adv_params_));
-
-  uint8_t flags = BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED;
-
-  // Service data represents a service UUID (2 bytes), followed by
-  // SERVICE_DATA_LEN bytes of data from our sensors.
-  ble_advdata_service_data_t advdata_service_data;
-  advdata_service_data.service_uuid = SERVICE_UUID;
-  advdata_service_data.data.p_data = service_data;
-  advdata_service_data.data.size = SERVICE_DATA_LEN;
-
-  advdata.name_type = BLE_ADVDATA_FULL_NAME;
-  advdata.flags = flags;
-
-  advdata.p_service_data_array = &advdata_service_data;
-  advdata.service_data_count = 1;
+  UNUSED_VARIABLE(adv_data_);
+  UNUSED_VARIABLE(advdata_service_data_);
 
   // We'll just broadcast our data, so we disallow connections and scan
   // requests.
@@ -73,11 +74,11 @@ static void init_advertisement_data() {
 
   ble_gap_conn_sec_mode_t sec_mode;
   BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);
-  sd_ble_gap_device_name_set(&sec_mode, (const uint8_t *)NAME, strlen(NAME));
+  sd_ble_gap_device_name_set(&sec_mode, (const uint8_t *)PRST_BLE_ADV_NAME,
+                             strlen(PRST_BLE_ADV_NAME));
 
-  // Encodes the advdata into encoded_adv_data.
-  uint32_t err_code = ble_advdata_encode(&advdata, adv_data_.adv_data.p_data,
-                                         &adv_data_.adv_data.len);
+  uint32_t err_code =
+      sd_ble_gap_adv_set_configure(&adv_handle_, &gap_adv_data_, &adv_params_);
   APP_ERROR_CHECK(err_code);
 }
 
@@ -101,8 +102,11 @@ void prst_ble_init() {
 }
 
 void prst_ble_update_adv_data(uint8_t n) {
-  uint32_t err_code =
-      sd_ble_gap_adv_set_configure(&adv_handle_, &adv_data_, &adv_params_);
+  service_data[0] = n;
+
+  // Encodes adv_data_ into .gap_adv_data_.
+  uint32_t err_code = ble_advdata_encode(
+      &adv_data_, gap_adv_data_.adv_data.p_data, &gap_adv_data_.adv_data.len);
   APP_ERROR_CHECK(err_code);
 }
 
@@ -110,11 +114,12 @@ void prst_adv_start() {
   ret_code_t err_code;
   err_code = sd_ble_gap_adv_start(adv_handle_, PRST_CONN_CFG_TAG);
   APP_ERROR_CHECK(err_code);
-  // NRF_LOG_INFO("Advertising started\n.");
+  NRF_LOG_INFO("Advertising started.\n");
 }
 
 void prst_adv_stop() {
   ret_code_t err_code;
   err_code = sd_ble_gap_adv_stop(adv_handle_);
   APP_ERROR_CHECK(err_code);
+  NRF_LOG_INFO("Advertising stopped.\n");
 }
\ No newline at end of file