diff --git a/tides2/bootloader/bootloader.cc b/tides2/bootloader/bootloader.cc
index 94df7eae2..b3bd24483 100755
--- a/tides2/bootloader/bootloader.cc
+++ b/tides2/bootloader/bootloader.cc
@@ -231,7 +231,7 @@ int main(void) {
   Init();
   InitializeReception();
 
-  bool exit_updater = !switches.pressed_immediate(SWITCH_MODE);
+  bool exit_updater = !switches.pressed_immediate(SWITCH_RANGE);
   while (!exit_updater) {
     bool error = false;
 
diff --git a/tides2/drivers/switches.h b/tides2/drivers/switches.h
index 97ab9fc0e..60bf484da 100755
--- a/tides2/drivers/switches.h
+++ b/tides2/drivers/switches.h
@@ -63,8 +63,10 @@ class Switches {
   }
   
   inline bool pressed_immediate(Switch s) const {
-    if (s == SWITCH_MODE) {
+    if (s == SWITCH_RANGE) {
       return !GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_2);
+    } else if (s == SWITCH_SHIFT) {
+      return !GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_13);
     } else {
       return false;
     }
diff --git a/tides2/settings.h b/tides2/settings.h
index 78ed7b051..01ec82466 100644
--- a/tides2/settings.h
+++ b/tides2/settings.h
@@ -63,7 +63,8 @@ struct State {
   uint8_t mode;
   uint8_t range;
   uint8_t output_mode;
-  uint8_t padding[5];
+  uint8_t color_blind;
+  uint8_t padding[4];
   
   enum { tag = 0x54415453 };  // STAT
 };
diff --git a/tides2/ui.cc b/tides2/ui.cc
index 51aecd43c..b00054813 100755
--- a/tides2/ui.cc
+++ b/tides2/ui.cc
@@ -59,6 +59,16 @@ void Ui::Init(Settings* settings, FactoryTest* factory_test) {
   factory_test_ = factory_test;
   mode_ = UI_MODE_NORMAL;
   
+  if (switches_.pressed_immediate(SWITCH_SHIFT)) {
+    State* state = settings_->mutable_state();
+    if (state->color_blind == 1) {
+      state->color_blind = 0;
+    } else {
+      state->color_blind = 1;
+    }
+    settings_->SaveState();
+  }
+  
   queue_.Init();
   
   fill(&press_time_[0], &press_time_[SWITCH_LAST], 0);
@@ -95,6 +105,26 @@ void Ui::Poll() {
   }
 }
 
+LedColor Ui::MakeColor(uint8_t value, bool color_blind) {
+  LedColor color = palette_[value];
+  if (color_blind) {
+    uint8_t pwm_counter = system_clock.milliseconds() & 15;
+    uint8_t triangle = (system_clock.milliseconds() >> 5) & 31;
+    triangle = triangle < 16 ? triangle : 31 - triangle;
+
+    if (value == 0) {
+      color = pwm_counter < (4 + (triangle >> 2))
+          ? LED_COLOR_GREEN
+          : LED_COLOR_OFF;
+    } else if (value == 1) {
+      color = LED_COLOR_YELLOW;
+    } else if (value == 2) {
+      color = pwm_counter == 0 ? LED_COLOR_RED : LED_COLOR_OFF;
+    }
+  }
+  return color;
+}
+
 void Ui::UpdateLEDs() {
   leds_.Clear();
   
@@ -104,9 +134,11 @@ void Ui::UpdateLEDs() {
     case UI_MODE_NORMAL:
       {
         const State& s = settings_->state();
-        leds_.set(LED_MODE, palette_[s.mode]);
-        leds_.set(LED_RANGE, palette_[s.range]);
-        leds_.set(LED_SHIFT, palette_[(s.output_mode + 3) % 4]);
+        bool color_blind = s.color_blind == 1;
+        
+        leds_.set(LED_MODE, MakeColor(s.mode, color_blind));
+        leds_.set(LED_RANGE, MakeColor(s.range, color_blind));
+        leds_.set(LED_SHIFT, MakeColor((s.output_mode + 3) % 4, color_blind));
       }
       break;
       
diff --git a/tides2/ui.h b/tides2/ui.h
index 899820537..aed374ce9 100755
--- a/tides2/ui.h
+++ b/tides2/ui.h
@@ -67,6 +67,7 @@ class Ui {
   void OnSwitchPressed(const stmlib::Event& e);
   void OnSwitchReleased(const stmlib::Event& e);
    
+  LedColor MakeColor(uint8_t value, bool color_blind);
   void UpdateLEDs();
 
   stmlib::EventQueue<16> queue_;