diff --git a/buttons.h b/buttons.h
index 6f72f6c..3be59b1 100644
--- a/buttons.h
+++ b/buttons.h
@@ -21,9 +21,6 @@
 #define BUTTON_STATE_INCREMENT (BUTTON_PRESSED_STATE/BUTTON_SAMPLES_PRESSED)
 #define BUTTON_STATE_DECREMENT (BUTTON_PRESSED_STATE/BUTTON_SAMPLES_RELEASED)
 
-#define BUTTON_SCAN_RATE 200    // [Hz] button scanning interrupt rate
-#define BUTTON_INT_PRIORITY 32  // button interrupt priority (higher number is lower priority)
-
 #define BUTTON_AUTOREPEAT_INITIAL 100   // how many samples must read pressed before autorepeat starts
 #define BUTTON_AUTOREPEAT_NEXT 10       // how many samples must read pressed before the next repetition
 
diff --git a/main.c b/main.c
index a59aac4..fc22d5c 100644
--- a/main.c
+++ b/main.c
@@ -209,8 +209,7 @@ void handle_user_input() {
 
         switch (button) {
             case S1: // toggle edge
-                trigger_mode++;
-                trigger_mode %= 3;
+                trigger_mode = (trigger_mode + 1) % 3;
                 break;
             case Up: // next scale
                 voltage_scale = (voltage_scale + 1) % VOLTAGE_SCALES;