diff --git a/src/main/java/de/neemann/digital/gui/components/test/Value.java b/src/main/java/de/neemann/digital/gui/components/test/Value.java
index 13265a1dd..b7444e42e 100644
--- a/src/main/java/de/neemann/digital/gui/components/test/Value.java
+++ b/src/main/java/de/neemann/digital/gui/components/test/Value.java
@@ -12,7 +12,24 @@ public class Value {
     /**
      * Types of values
      */
-    public enum Type {NORMAL, DONTCARE, HIGHZ, CLOCK}
+    public enum Type {
+        /**
+         * normal value, value is stored in member variable value
+         */
+        NORMAL,
+        /**
+         * Value don't care in test
+         */
+        DONTCARE,
+        /**
+         * value is "high impedance"
+         */
+        HIGHZ,
+        /**
+         * its a clock value which is handled as a 0-1-0 sequence
+         */
+        CLOCK
+    }
 
     private final long value;
     private final Type type;
@@ -71,6 +88,9 @@ public class Value {
 
         if (v.type != type) return false;
 
+        // both types are equal!
+        if (type == Type.HIGHZ) return true;
+
         return value == v.value;
     }
 
diff --git a/src/test/java/de/neemann/digital/gui/components/test/TestResultTest.java b/src/test/java/de/neemann/digital/gui/components/test/TestResultTest.java
index 17f93340c..98cd215a8 100644
--- a/src/test/java/de/neemann/digital/gui/components/test/TestResultTest.java
+++ b/src/test/java/de/neemann/digital/gui/components/test/TestResultTest.java
@@ -61,7 +61,7 @@ public class TestResultTest extends TestCase {
         assertEquals(false, ((MatchedValue)tr.getValue(3,2)).isPassed());
     }
 
-    public void testResultErrorDC() throws Exception {
+    public void testResultDontCare() throws Exception {
         Model model = getModel("A+B");
         TestData data = new TestData(
                 "A B Y\n"
@@ -73,4 +73,16 @@ public class TestResultTest extends TestCase {
         assertTrue(tr.allPassed());
     }
 
+    public void testResultDontCare2() throws Exception {
+        Model model = getModel("A+B");
+        TestData data = new TestData(
+                "A B Y\n"
+                        + "0 0 x\n"
+                        + "0 1 1\n"
+                        + "1 0 1\n"
+                        + "1 1 1\n");
+        TestResult tr = new TestResult(data).create(model);
+        assertTrue(tr.allPassed());
+    }
+
 }
\ No newline at end of file
diff --git a/src/test/java/de/neemann/digital/integration/TestTestableExamples.java b/src/test/java/de/neemann/digital/integration/TestTestableExamples.java
index 0da2d8096..acb94aa7c 100644
--- a/src/test/java/de/neemann/digital/integration/TestTestableExamples.java
+++ b/src/test/java/de/neemann/digital/integration/TestTestableExamples.java
@@ -24,9 +24,13 @@ public class TestTestableExamples extends TestCase {
 
     public void testTestableTest() throws Exception {
         File examples = new File(Resources.getRoot(), "/dig/test");
-        assertEquals(2, new FileScanner(this::check).scan(examples));
+        assertEquals(3, new FileScanner(this::check).scan(examples));
     }
 
+//    public void testFile() throws Exception {
+//        check(new File(Resources.getRoot(), "/dig/test/highz.dig"));
+//    }
+
     /**
      * Loads the model and initializes and tests it
      *
diff --git a/src/test/resources/dig/test/highz.dig b/src/test/resources/dig/test/highz.dig
new file mode 100644
index 000000000..10eb58a2b
--- /dev/null
+++ b/src/test/resources/dig/test/highz.dig
@@ -0,0 +1,87 @@
+<?xml version="1.0" encoding="utf-8"?>
+<circuit>
+  <version>1</version>
+  <visualElements>
+    <visualElement>
+      <elementName>Driver</elementName>
+      <elementAttributes>
+        <entry>
+          <string>flipSelPos</string>
+          <boolean>true</boolean>
+        </entry>
+      </elementAttributes>
+      <pos x="360" y="300"/>
+    </visualElement>
+    <visualElement>
+      <elementName>In</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>I</string>
+        </entry>
+      </elementAttributes>
+      <pos x="300" y="300"/>
+    </visualElement>
+    <visualElement>
+      <elementName>In</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>en</string>
+        </entry>
+      </elementAttributes>
+      <pos x="300" y="340"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>O</string>
+        </entry>
+      </elementAttributes>
+      <pos x="420" y="300"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Testcase</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>High Z</string>
+        </entry>
+        <entry>
+          <string>Testdata</string>
+          <testData>
+            <dataString>I en O
+1 1  1
+0 1  0
+1 0  Z
+0 0  Z
+1 0  X
+0 0  X
+</dataString>
+          </testData>
+        </entry>
+      </elementAttributes>
+      <pos x="320" y="420"/>
+    </visualElement>
+  </visualElements>
+  <wires>
+    <wire>
+      <p1 x="300" y="340"/>
+      <p2 x="360" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="300" y="300"/>
+      <p2 x="340" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="300"/>
+      <p2 x="420" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="360" y="320"/>
+      <p2 x="360" y="340"/>
+    </wire>
+  </wires>
+</circuit>
\ No newline at end of file