diff --git a/README.md b/README.md
index 48ad69c..0e2af9b 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,14 @@ I used an Adafruit Pro Trinket for mine, which has 150+ lights.
 
 Of course, a standard Arduino will work just fine too!
 
+This was coded to color-correct a specific type of GRB LEDs on wires I got from Amazon.
+It's coded to match the lights we already have, which are biased toward yellow and amber.
+
+You may have gotten lights wired RGB, in which case this is going to look very green.
+It should be just a matter of switching the first two bytes in each color definition
+to go from GRB to RGB.
+
+
 
 Setup
 -------
@@ -34,7 +42,7 @@ You can plug the LED strip into the +5v on the power supply;
 You can power your microcontroller from the beefier power supply, too,
 so you don't have to run USB just to power the microcontroller.
 
-This was coded to color-correct a specific type of GRB LEDs on wires I got from Amazon.
-It's coded to match the lights we already have, which are biased toward yellow and amber.
-Some of the lights are wired differently and the colors are going to be wrong.
-Play around, commenting out all but one color, to see if it's right.
+The code as written wants pin 4 to be connected to ground.
+When you disconnect it,
+the whole strand goes white.
+My family has a tradition of the tree going from colors to white on the morning of the 25th.
diff --git a/holiday-lights.ino b/holiday-lights.ino
index 6ae9e08..866ced3 100644
--- a/holiday-lights.ino
+++ b/holiday-lights.ino
@@ -6,6 +6,8 @@
 #define PIN 6
 #define NUM_LEDS 150
 
+#define WHITE_PIN 4
+
 Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_LEDS, PIN, NEO_GRB | NEO_KHZ800);
 
 const uint32_t colors[] = {
@@ -24,18 +26,40 @@ const int ncolors = sizeof(colors) / sizeof(*colors);
 void setup() {
   strip.begin();
   strip.show();
+  pinMode(WHITE_PIN, INPUT_PULLUP);
 }
 
-void loop() {
-  for (int i = 0; i < 12; i += 1) {
+void loop_color() {
+  for (int i = 0; i < NUM_LEDS/12; i += 1) {
     int pos = random(NUM_LEDS);
     if (random(100) < 20) {
-      int color = random(ncolors);
-      strip.setPixelColor(pos, colors[color]);
-    } else {
-      strip.setPixelColor(pos, 0);
-    }
+     int color = random(ncolors);
+     strip.setPixelColor(pos, colors[color]);
+   } else {
+     strip.setPixelColor(pos, 0);
+   }
   }
   strip.show();
   delay(240);
 }
+
+void loop_white() {
+  for (int i = 0; i < NUM_LEDS/12; i += 1) {
+    int pos = random(NUM_LEDS);
+    if (random(100) < 5) {
+      strip.setPixelColor(pos, 0x0);
+    } else {
+      strip.setPixelColor(pos, 0x99ffaa);
+    }
+  }
+  strip.show();
+  delay(24);
+}
+
+void loop() {
+  if (digitalRead(WHITE_PIN)) {
+    loop_white();
+  } else {
+    loop_color();
+  }
+}