diff --git a/src/main/java/de/neemann/digital/draw/shapes/ButtonLEDShape.java b/src/main/java/de/neemann/digital/draw/shapes/ButtonLEDShape.java
index 2dd6d0d04..7db3bf484 100644
--- a/src/main/java/de/neemann/digital/draw/shapes/ButtonLEDShape.java
+++ b/src/main/java/de/neemann/digital/draw/shapes/ButtonLEDShape.java
@@ -71,7 +71,7 @@ public class ButtonLEDShape extends ButtonShape {
     public void drawTo(Graphic graphic, Style heighLight) {
         super.drawTo(graphic, heighLight);
 
-        boolean ledOn = ledValue == null || ledValue.getBool();
+        boolean ledOn = ledValue == null || (ledValue.getBool() & !ledValue.isHighZ());
         boolean pressed = button != null && button.isPressed();
 
         Vector center;
diff --git a/src/main/java/de/neemann/digital/draw/shapes/RGBLEDShape.java b/src/main/java/de/neemann/digital/draw/shapes/RGBLEDShape.java
index 78a30ccb9..a9c3a0195 100644
--- a/src/main/java/de/neemann/digital/draw/shapes/RGBLEDShape.java
+++ b/src/main/java/de/neemann/digital/draw/shapes/RGBLEDShape.java
@@ -6,6 +6,7 @@
 package de.neemann.digital.draw.shapes;
 
 import de.neemann.digital.core.Bits;
+import de.neemann.digital.core.ObservableValue;
 import de.neemann.digital.core.element.ElementAttributes;
 import de.neemann.digital.core.element.Keys;
 import de.neemann.digital.core.element.PinDescriptions;
@@ -67,13 +68,20 @@ public class RGBLEDShape implements Shape {
     @Override
     public void readObservableValues() {
         if (ioState != null) {
-            long r = ioState.getInput(0).getValue() * 255 / max;
-            long g = ioState.getInput(1).getValue() * 255 / max;
-            long b = ioState.getInput(2).getValue() * 255 / max;
+            long r = getCol(ioState.getInput(0));
+            long g = getCol(ioState.getInput(1));
+            long b = getCol(ioState.getInput(2));
             color = new Color((int) r, (int) g, (int) b);
         }
     }
 
+    long getCol(ObservableValue c) {
+        if (c.isHighZ())
+            return 0;
+        else
+            return c.getValue() * 255 / max;
+    }
+
     @Override
     public void drawTo(Graphic graphic, Style heighLight) {
         if (color == null)