diff --git a/lib/Cross/Gun/Atmega328pHal.cpp b/lib/Cross/Gun/Atmega328pHal.cpp
index 5e59b10..16121bd 100644
--- a/lib/Cross/Gun/Atmega328pHal.cpp
+++ b/lib/Cross/Gun/Atmega328pHal.cpp
@@ -26,20 +26,21 @@
 #define VIBRATOR_PIN 6
 #define BATTERY_VOLTAGE_PIN A3
 #define CHARGING_STATE_PIN A2
-#define BUTTON2_PIN 3
+#define BUTTON_PIN 3
 #define TRIGGER_PIN 2
 
 #define MIN_BAT_VOLTAGE 3000
 #define MAX_BAT_VOLTAGE 4120
 
 Atmega328pHal::Atmega328pHal() {
-
   pinMode(VIBRATOR_PIN, OUTPUT);
   pinMode(LASER_PIN, OUTPUT);
+  pinMode(TRIGGER_PIN, INPUT_PULLUP);
+  pinMode(BUTTON_PIN, INPUT_PULLUP);
 }
 
 bool Atmega328pHal::triggerIsUp() { return bit_is_set(PIND, PD2); }
-bool Atmega328pHal::buttonIsUp() { return bit_is_set(PIND, PD3); }
+bool Atmega328pHal::buttonIsUp() { return bit_is_clear(PIND, PD3); }
 
 /*
  * the 'loop' method shall be called each 10ms
@@ -89,17 +90,14 @@ void Atmega328pHal::sleep() {
                 USART0_OFF, TWI_OFF);
 }
 
-void Atmega328pHal::setGun(Gun *gun) { gun = gun; }
+void Atmega328pHal::setGun(Gun *gun) { this->gun = gun; }
 
 extern void buttonInterruptHandler();
-void Atmega328pHal::configureInputCallbacks() {
+extern void triggerInterruptHandler();
 
-  pinMode(BUTTON2_PIN, INPUT_PULLUP);
-  attachInterrupt(digitalPinToInterrupt(BUTTON2_PIN), buttonInterruptHandler,
+void Atmega328pHal::configureInputCallbacks() {
+  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), buttonInterruptHandler,
                   CHANGE);
-
-  extern void triggerInterruptHandler();
-  pinMode(TRIGGER_PIN, INPUT_PULLUP);
   attachInterrupt(digitalPinToInterrupt(TRIGGER_PIN), triggerInterruptHandler,
                   CHANGE);
 }
\ No newline at end of file
diff --git a/lib/Cross/Gun/SSD1306Ui.hpp b/lib/Cross/Gun/SSD1306Ui.hpp
index 7920620..6fd6b28 100644
--- a/lib/Cross/Gun/SSD1306Ui.hpp
+++ b/lib/Cross/Gun/SSD1306Ui.hpp
@@ -95,13 +95,13 @@ class SSD1306Ui : public IGunUi {
   }
 
   void clearCalibration() override {
-    display.fillRect(2, 10, 126, 14, 0); // clear
+    display.fillRect(2, 10, 126, 22, 0); // clear
   }
 
   void displayCalibration() override {
     display.clearDisplay();
-    display.setCursor(2, 25);
     display.setFont(&FreeMonoOblique9pt7b);
+    display.setCursor(2, 25);
     display.print("Calibration");
     display.display();
   }
diff --git a/src/GunApp.cpp b/src/GunApp.cpp
index fa32e66..5e195ec 100644
--- a/src/GunApp.cpp
+++ b/src/GunApp.cpp
@@ -23,27 +23,31 @@ SSD1306Ui ui;
 Atmega328pHal hal;
 Gun gun(&hal, &ui);
 
-volatile bool tick = false;
-ISR(TIMER2_COMPA_vect) { tick = true; }
+volatile bool applicativeEvent = false;
+ISR(TIMER2_COMPA_vect) { applicativeEvent = true; }
 
 volatile Contactor::Event pendingTriggerEvent;
 void triggerInterruptHandler() {
-  if (hal.triggerIsUp()) {
-    pendingTriggerEvent = Contactor::Event::Released;
-  } else {
-    pendingTriggerEvent = Contactor::Event::Pressed;
+  if (Contactor::Event::NoEvent == pendingTriggerEvent) {
+    if (hal.triggerIsUp()) {
+      pendingTriggerEvent = Contactor::Event::Released;
+    } else {
+      pendingTriggerEvent = Contactor::Event::Pressed;
+    }
+    applicativeEvent = true;
   }
-  tick = true;
 }
 
 volatile Contactor::Event pendingButtonEvent;
 void buttonInterruptHandler() {
-  if (hal.buttonIsUp()) {
-    pendingButtonEvent = Contactor::Event::Released;
-  } else {
-    pendingButtonEvent = Contactor::Event::Pressed;
+  if (Contactor::Event::NoEvent == pendingButtonEvent) {
+    if (hal.buttonIsUp()) {
+      pendingButtonEvent = Contactor::Event::Released;
+    } else {
+      pendingButtonEvent = Contactor::Event::Pressed;
+    }
+    applicativeEvent = true;
   }
-  tick = true;
 }
 
 void loop(void) {
@@ -53,16 +57,19 @@ void loop(void) {
   // and counter1, used internally by the Arduino
   // framework. Avoid processing these wakeups as
   // applicative events using 'tick' control variable.
-  
-  if (tick) {
+
+  if (applicativeEvent) {
+    applicativeEvent = false;
+
     // wire interrupt-based events with main code
     gun.trigger.pendingEvent = pendingTriggerEvent;
     gun.button.pendingEvent = pendingButtonEvent;
+
+    gun.loop();
+
     pendingTriggerEvent = Contactor::Event::NoEvent;
     pendingButtonEvent = Contactor::Event::NoEvent;
 
-    gun.loop();
-    tick = false;
     hal.sleep();
   }
 }
diff --git a/test/native/test_gun/gun.cpp b/test/native/test_gun/gun.cpp
index 63fa00d..4ecc02b 100644
--- a/test/native/test_gun/gun.cpp
+++ b/test/native/test_gun/gun.cpp
@@ -191,12 +191,43 @@ void expect_trigger_to_have_no_effect_in_calibration_mode() {
   Verify(Method(mockHal, laserOff)).Exactly(0);
 }
 
+void expect_long_press_to_trigger_only_if_button_is_down() {
+  Mock<IGunUi> mockUi;
+  Mock<IGunHal> mockHal;
+
+  MOCK_ALL();
+
+  IGunUi &ui = mockUi.get();
+  IGunHal &hal = mockHal.get();
+
+  Gun gun(&hal, &ui);
+
+  gun.button.pendingEvent = Contactor::Event::Pressed;
+  gun.loop();
+
+  gun.button.pendingEvent = Contactor::Event::Released;
+  gun.loop();
+
+  for (uint8_t tickCounter = 0; tickCounter <= 200; tickCounter++) {
+    // long press shall be accounted after 2s, 200 ticks
+    gun.loop();
+  }
+
+  // No long press, no switch to calibration
+  Verify(Method(mockHal, laserOn)).Exactly(0);
+  Verify(Method(mockUi, displayCalibration)).Exactly(0);
+  Verify(Method(mockHal, laserOff)).Exactly(0);
+  Verify(Method(mockUi, clearCalibration)).Exactly(0);
+  Verify(Method(mockUi, displayShootCount)).Exactly(1);
+}
+
 int main(int, char **) {
   UNITY_BEGIN();
   RUN_TEST(expect_gun_to_loop);
   RUN_TEST(expect_gun_to_shoot_50ms_on_trigger_down);
   RUN_TEST(expect_ui_to_display_battery_state_at_boot_and_each_1s);
   RUN_TEST(expect_switch_to_maintenance_after_2s_button_continuous_press);
+  RUN_TEST(expect_long_press_to_trigger_only_if_button_is_down);
   RUN_TEST(expect_button_press_to_reset_shoot_count_and_redisplay);
   RUN_TEST(expect_trigger_to_have_no_effect_in_calibration_mode);