diff --git a/src/displayapp/screens/Brightness.cpp b/src/displayapp/screens/Brightness.cpp
index 9e3416c0..8ea9a771 100644
--- a/src/displayapp/screens/Brightness.cpp
+++ b/src/displayapp/screens/Brightness.cpp
@@ -11,15 +11,15 @@ void slider_event_cb(lv_obj_t * slider, lv_event_t event) {
 }
 
 Brightness::Brightness(Pinetime::Applications::DisplayApp *app, Controllers::BrightnessController& brightness) : Screen(app), brightness{brightness} {
-  slider = lv_slider_create(lv_scr_act(), NULL);
+  slider = lv_slider_create(lv_scr_act(), nullptr);
   lv_obj_set_user_data(slider, this);
   lv_obj_set_width(slider, LV_DPI * 2);
-  lv_obj_align(slider, NULL, LV_ALIGN_CENTER, 0, 0);
+  lv_obj_align(slider, nullptr, LV_ALIGN_CENTER, 0, 0);
   lv_obj_set_event_cb(slider, slider_event_cb);
   lv_slider_set_range(slider, 0, 2);
   lv_slider_set_value(slider, LevelToInt(brightness.Level()), LV_ANIM_OFF);
 
-  slider_label = lv_label_create(lv_scr_act(), NULL);
+  slider_label = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(slider_label, LevelToString(brightness.Level()));
   lv_obj_set_auto_realign(slider_label, true);
   lv_obj_align(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);
diff --git a/src/displayapp/screens/Clock.cpp b/src/displayapp/screens/Clock.cpp
index 243d4c04..bb14d520 100644
--- a/src/displayapp/screens/Clock.cpp
+++ b/src/displayapp/screens/Clock.cpp
@@ -29,28 +29,28 @@ Clock::Clock(DisplayApp* app,
   displayedChar[3] = 0;
   displayedChar[4] = 0;
 
-  batteryIcon = lv_label_create(lv_scr_act(), NULL);
+  batteryIcon = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(batteryIcon, Symbols::batteryFull);
   lv_obj_align(batteryIcon, lv_scr_act(), LV_ALIGN_IN_TOP_RIGHT, -5, 2);
 
-  batteryPlug = lv_label_create(lv_scr_act(), NULL);
+  batteryPlug = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(batteryPlug, Symbols::plug);
   lv_obj_align(batteryPlug, batteryIcon, LV_ALIGN_OUT_LEFT_MID, -5, 0);
 
-  bleIcon = lv_label_create(lv_scr_act(), NULL);
+  bleIcon = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(bleIcon, Symbols::bluetooth);
   lv_obj_align(bleIcon, batteryPlug, LV_ALIGN_OUT_LEFT_MID, -5, 0);
 
 
-  label_date = lv_label_create(lv_scr_act(), NULL);
+  label_date = lv_label_create(lv_scr_act(), nullptr);
 
   lv_obj_align(label_date, lv_scr_act(), LV_ALIGN_IN_LEFT_MID, 0, 60);
 
-  label_time = lv_label_create(lv_scr_act(), NULL);
+  label_time = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_style(label_time, LV_LABEL_STYLE_MAIN, LabelBigStyle);
   lv_obj_align(label_time, lv_scr_act(), LV_ALIGN_IN_LEFT_MID, 0, 0);
 
-  backgroundLabel = lv_label_create(lv_scr_act(), NULL);
+  backgroundLabel = lv_label_create(lv_scr_act(), nullptr);
   backgroundLabel->user_data = this;
   lv_obj_set_click(backgroundLabel, true);
   lv_obj_set_event_cb(backgroundLabel, event_handler);
@@ -60,23 +60,23 @@ Clock::Clock(DisplayApp* app,
   lv_label_set_text(backgroundLabel, "");
 
 
-  heartbeatIcon = lv_label_create(lv_scr_act(), NULL);
+  heartbeatIcon = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(heartbeatIcon, Symbols::heartBeat);
   lv_obj_align(heartbeatIcon, lv_scr_act(), LV_ALIGN_IN_BOTTOM_LEFT, 5, -2);
 
-  heartbeatValue = lv_label_create(lv_scr_act(), NULL);
+  heartbeatValue = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(heartbeatValue, "0");
   lv_obj_align(heartbeatValue, heartbeatIcon, LV_ALIGN_OUT_RIGHT_MID, 5, 0);
 
-  heartbeatBpm = lv_label_create(lv_scr_act(), NULL);
+  heartbeatBpm = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(heartbeatBpm, "BPM");
   lv_obj_align(heartbeatBpm, heartbeatValue, LV_ALIGN_OUT_RIGHT_MID, 5, 0);
 
-  stepValue = lv_label_create(lv_scr_act(), NULL);
+  stepValue = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(stepValue, "0");
   lv_obj_align(stepValue, lv_scr_act(), LV_ALIGN_IN_BOTTOM_RIGHT, -5, -2);
 
-  stepIcon = lv_label_create(lv_scr_act(), NULL);
+  stepIcon = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(stepIcon, Symbols::shoe);
   lv_obj_align(stepIcon, stepValue, LV_ALIGN_OUT_LEFT_MID, -5, 0);
 }
diff --git a/src/displayapp/screens/DropDownDemo.cpp b/src/displayapp/screens/DropDownDemo.cpp
index 735a0cce..ce3acd53 100644
--- a/src/displayapp/screens/DropDownDemo.cpp
+++ b/src/displayapp/screens/DropDownDemo.cpp
@@ -9,7 +9,7 @@ extern lv_font_t jetbrains_mono_bold_20;
 
 DropDownDemo::DropDownDemo(Pinetime::Applications::DisplayApp *app) : Screen(app) {
   // Create the dropdown object, with many item, and fix its height
-  ddlist = lv_ddlist_create(lv_scr_act(), NULL);
+  ddlist = lv_ddlist_create(lv_scr_act(), nullptr);
   lv_ddlist_set_options(ddlist, "Apple\n"
                                 "Banana\n"
                                 "Orange\n"
@@ -24,7 +24,7 @@ DropDownDemo::DropDownDemo(Pinetime::Applications::DisplayApp *app) : Screen(app
   lv_ddlist_set_fix_width(ddlist, 150);
   lv_ddlist_set_draw_arrow(ddlist, true);
   lv_ddlist_set_fix_height(ddlist, 150);
-  lv_obj_align(ddlist, NULL, LV_ALIGN_IN_TOP_MID, 0, 20);
+  lv_obj_align(ddlist, nullptr, LV_ALIGN_IN_TOP_MID, 0, 20);
 }
 
 DropDownDemo::~DropDownDemo() {
diff --git a/src/displayapp/screens/FirmwareUpdate.cpp b/src/displayapp/screens/FirmwareUpdate.cpp
index e831114d..778409eb 100644
--- a/src/displayapp/screens/FirmwareUpdate.cpp
+++ b/src/displayapp/screens/FirmwareUpdate.cpp
@@ -10,19 +10,19 @@ extern lv_font_t jetbrains_mono_bold_20;
 FirmwareUpdate::FirmwareUpdate(Pinetime::Applications::DisplayApp *app, Pinetime::Controllers::Ble& bleController) :
       Screen(app), bleController{bleController} {
 
-  titleLabel = lv_label_create(lv_scr_act(), NULL);
+  titleLabel = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(titleLabel, "Firmware update");
   lv_obj_set_auto_realign(titleLabel, true);
-  lv_obj_align(titleLabel, NULL, LV_ALIGN_IN_TOP_MID, 0, 50);
+  lv_obj_align(titleLabel, nullptr, LV_ALIGN_IN_TOP_MID, 0, 50);
 
-  bar1 = lv_bar_create(lv_scr_act(), NULL);
+  bar1 = lv_bar_create(lv_scr_act(), nullptr);
   lv_obj_set_size(bar1, 200, 30);
-  lv_obj_align(bar1, NULL, LV_ALIGN_CENTER, 0, 0);
+  lv_obj_align(bar1, nullptr, LV_ALIGN_CENTER, 0, 0);
   lv_bar_set_anim_time(bar1, 10);
   lv_bar_set_range(bar1, 0, 100);
   lv_bar_set_value(bar1, 0, LV_ANIM_OFF);
 
-  percentLabel = lv_label_create(lv_scr_act(), NULL);
+  percentLabel = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_text(percentLabel, "");
   lv_obj_set_auto_realign(percentLabel, true);
   lv_obj_align(percentLabel, bar1, LV_ALIGN_OUT_TOP_MID, 0, 60);
diff --git a/src/displayapp/screens/FirmwareValidation.cpp b/src/displayapp/screens/FirmwareValidation.cpp
index 2300b41d..4ac399ff 100644
--- a/src/displayapp/screens/FirmwareValidation.cpp
+++ b/src/displayapp/screens/FirmwareValidation.cpp
@@ -20,20 +20,20 @@ namespace {
 FirmwareValidation::FirmwareValidation(Pinetime::Applications::DisplayApp *app,
                                        Pinetime::Controllers::FirmwareValidator &validator)
                                        : Screen{app}, validator{validator} {
-  labelVersionInfo = lv_label_create(lv_scr_act(), NULL);
-  lv_obj_align(labelVersionInfo, NULL, LV_ALIGN_IN_TOP_LEFT, 0, 0);
+  labelVersionInfo = lv_label_create(lv_scr_act(), nullptr);
+  lv_obj_align(labelVersionInfo, nullptr, LV_ALIGN_IN_TOP_LEFT, 0, 0);
   lv_label_set_text(labelVersionInfo, "Version : ");
   lv_label_set_align(labelVersionInfo, LV_LABEL_ALIGN_LEFT);
 
 
-  labelVersionValue = lv_label_create(lv_scr_act(), NULL);
+  labelVersionValue = lv_label_create(lv_scr_act(), nullptr);
   lv_obj_align(labelVersionValue, labelVersionInfo, LV_ALIGN_OUT_RIGHT_MID, 0, 0);
   lv_label_set_recolor(labelVersionValue, true);
   sprintf(version, "%ld.%ld.%ld", Version::Major(), Version::Minor(), Version::Patch());
   lv_label_set_text(labelVersionValue, version);
 
-  labelIsValidated = lv_label_create(lv_scr_act(), NULL);
-  lv_obj_align(labelIsValidated, NULL, LV_ALIGN_IN_TOP_LEFT, 0, 50);
+  labelIsValidated = lv_label_create(lv_scr_act(), nullptr);
+  lv_obj_align(labelIsValidated, nullptr, LV_ALIGN_IN_TOP_LEFT, 0, 50);
   lv_label_set_recolor(labelIsValidated, true);
   lv_label_set_long_mode(labelIsValidated, LV_LABEL_LONG_BREAK);
   lv_obj_set_width(labelIsValidated, 240);
@@ -44,21 +44,21 @@ FirmwareValidation::FirmwareValidation(Pinetime::Applications::DisplayApp *app,
     lv_label_set_text(labelIsValidated,
                       "Please #00ff00 Validate# this version or\n#ff0000 Reset# to rollback to the previous version.");
 
-    buttonValidate = lv_btn_create(lv_scr_act(), NULL);
+    buttonValidate = lv_btn_create(lv_scr_act(), nullptr);
     lv_obj_align(buttonValidate, NULL, LV_ALIGN_IN_BOTTOM_LEFT, 0, 0);
     buttonValidate->user_data = this;
     lv_obj_set_event_cb(buttonValidate, ButtonEventHandler);
 
-    labelButtonValidate = lv_label_create(buttonValidate, NULL);
+    labelButtonValidate = lv_label_create(buttonValidate, nullptr);
     lv_label_set_recolor(labelButtonValidate, true);
     lv_label_set_text(labelButtonValidate, "#00ff00 Validate#");
 
-    buttonReset = lv_btn_create(lv_scr_act(), NULL);
+    buttonReset = lv_btn_create(lv_scr_act(), nullptr);
     buttonReset->user_data = this;
-    lv_obj_align(buttonReset, NULL, LV_ALIGN_IN_BOTTOM_RIGHT, 0, 0);
+    lv_obj_align(buttonReset, nullptr, LV_ALIGN_IN_BOTTOM_RIGHT, 0, 0);
     lv_obj_set_event_cb(buttonReset, ButtonEventHandler);
 
-    labelButtonReset = lv_label_create(buttonReset, NULL);
+    labelButtonReset = lv_label_create(buttonReset, nullptr);
     lv_label_set_recolor(labelButtonReset, true);
     lv_label_set_text(labelButtonReset, "#ff0000 Reset#");
   }
diff --git a/src/displayapp/screens/Gauge.cpp b/src/displayapp/screens/Gauge.cpp
index fd905231..81c283ca 100644
--- a/src/displayapp/screens/Gauge.cpp
+++ b/src/displayapp/screens/Gauge.cpp
@@ -25,11 +25,11 @@ Gauge::Gauge(Pinetime::Applications::DisplayApp *app) : Screen(app) {
   needle_colors[0] = LV_COLOR_ORANGE;
 
   /*Create a gauge*/
-  gauge1 = lv_gauge_create(lv_scr_act(), NULL);
+  gauge1 = lv_gauge_create(lv_scr_act(), nullptr);
   lv_gauge_set_style(gauge1, LV_GAUGE_STYLE_MAIN, &style);
   lv_gauge_set_needle_count(gauge1, 1, needle_colors);
   lv_obj_set_size(gauge1, 180, 180);
-  lv_obj_align(gauge1, NULL, LV_ALIGN_CENTER, 0, 0);
+  lv_obj_align(gauge1, nullptr, LV_ALIGN_CENTER, 0, 0);
   lv_gauge_set_scale(gauge1, 360, 60, 0);
   lv_gauge_set_range(gauge1, 0, 59);
 
diff --git a/src/displayapp/screens/Label.cpp b/src/displayapp/screens/Label.cpp
index 780ee88e..540776cc 100644
--- a/src/displayapp/screens/Label.cpp
+++ b/src/displayapp/screens/Label.cpp
@@ -4,7 +4,7 @@
 using namespace Pinetime::Applications::Screens;
 
 Label::Label(Pinetime::Applications::DisplayApp *app, const char *text)  : Screen(app), text{text} {
-  label = lv_label_create(lv_scr_act(), NULL);
+  label = lv_label_create(lv_scr_act(), nullptr);
   lv_label_set_align(label, LV_LABEL_ALIGN_LEFT);
   lv_obj_set_size(label, 240, 240);
   lv_label_set_text(label, text);
diff --git a/src/displayapp/screens/Meter.cpp b/src/displayapp/screens/Meter.cpp
index c74b8bdf..273e111d 100644
--- a/src/displayapp/screens/Meter.cpp
+++ b/src/displayapp/screens/Meter.cpp
@@ -17,14 +17,14 @@ Meter::Meter(Pinetime::Applications::DisplayApp *app) : Screen(app) {
   style_lmeter.body.padding.left = 16;                           /*Line length*/
 
   /*Create a line meter */
-  lmeter = lv_lmeter_create(lv_scr_act(), NULL);
+  lmeter = lv_lmeter_create(lv_scr_act(), nullptr);
   lv_lmeter_set_range(lmeter, 0, 60);                   /*Set the range*/
   lv_lmeter_set_value(lmeter, value);                       /*Set the current value*/
   lv_lmeter_set_angle_offset(lmeter, 180);
   lv_lmeter_set_scale(lmeter, 360, 60);                  /*Set the angle and number of lines*/
   lv_lmeter_set_style(lmeter, LV_LMETER_STYLE_MAIN, &style_lmeter);           /*Apply the new style*/
   lv_obj_set_size(lmeter, 150, 150);
-  lv_obj_align(lmeter, NULL, LV_ALIGN_CENTER, 0, 0);
+  lv_obj_align(lmeter, nullptr, LV_ALIGN_CENTER, 0, 0);
 
 }
 
diff --git a/src/displayapp/screens/Modal.cpp b/src/displayapp/screens/Modal.cpp
index 63ae70c0..29f7bfa7 100644
--- a/src/displayapp/screens/Modal.cpp
+++ b/src/displayapp/screens/Modal.cpp
@@ -54,7 +54,7 @@ void Modal::Show(const char* msg) {
   modal_style.body.main_color = modal_style.body.grad_color = LV_COLOR_BLACK;
   modal_style.body.opa = LV_OPA_50;
 
-  obj = lv_obj_create(lv_scr_act(), NULL);
+  obj = lv_obj_create(lv_scr_act(), nullptr);
   lv_obj_set_style(obj, &modal_style);
   lv_obj_set_pos(obj, 0, 0);
   lv_obj_set_size(obj, LV_HOR_RES, LV_VER_RES);
@@ -63,10 +63,10 @@ void Modal::Show(const char* msg) {
   static const char * btns2[] = {"Ok", ""};
 
   /* Create the message box as a child of the modal background */
-  mbox = lv_mbox_create(obj, NULL);
+  mbox = lv_mbox_create(obj, nullptr);
   lv_mbox_add_btns(mbox, btns2);
   lv_mbox_set_text(mbox, msg);
-  lv_obj_align(mbox, NULL, LV_ALIGN_CENTER, 0, 0);
+  lv_obj_align(mbox, nullptr, LV_ALIGN_CENTER, 0, 0);
   lv_obj_set_event_cb(mbox, Modal::mbox_event_cb);
 
   mbox->user_data = this;
diff --git a/src/displayapp/screens/Tile.cpp b/src/displayapp/screens/Tile.cpp
index deb88472..75fa6ef5 100644
--- a/src/displayapp/screens/Tile.cpp
+++ b/src/displayapp/screens/Tile.cpp
@@ -30,7 +30,7 @@ Tile::Tile(DisplayApp* app, std::array<Applications, 6>& applications) : Screen(
   }
   modal.reset(new Modal(app));
 
-  btnm1 = lv_btnm_create(lv_scr_act(), NULL);
+  btnm1 = lv_btnm_create(lv_scr_act(), nullptr);
   lv_btnm_set_map(btnm1, btnm_map1);
   lv_obj_set_size(btnm1, LV_HOR_RES, LV_VER_RES);
 
diff --git a/src/systemtask/SystemMonitor.h b/src/systemtask/SystemMonitor.h
index ec1fd817..029a1364 100644
--- a/src/systemtask/SystemMonitor.h
+++ b/src/systemtask/SystemMonitor.h
@@ -27,7 +27,7 @@ namespace Pinetime {
         void Process() const {
           if(xTaskGetTickCount() - lastTick > 10000) {
             NRF_LOG_INFO("---------------------------------------\nFree heap : %d", xPortGetFreeHeapSize());
-            auto nb = uxTaskGetSystemState(tasksStatus, 10, NULL);
+            auto nb = uxTaskGetSystemState(tasksStatus, 10, nullptr);
             for (uint32_t i = 0; i < nb; i++) {
               NRF_LOG_INFO("Task [%s] - %d", tasksStatus[i].pcTaskName, tasksStatus[i].usStackHighWaterMark);
               if (tasksStatus[i].usStackHighWaterMark < 20)