diff --git a/src/main/java/de/neemann/digital/core/switching/PlainSwitch.java b/src/main/java/de/neemann/digital/core/switching/PlainSwitch.java
index 2f146abb3..23bfb8e23 100644
--- a/src/main/java/de/neemann/digital/core/switching/PlainSwitch.java
+++ b/src/main/java/de/neemann/digital/core/switching/PlainSwitch.java
@@ -94,7 +94,7 @@ public final class PlainSwitch implements NodeInterface {
                 else {
                     constant = in2.searchConstant();
                     if (constant != null)
-                        return new UniDirectionalSwitch(constant, output1, setOpenContactToHighZ);
+                        return new UniDirectionalSwitch(constant, output1, true);
                     else
                         return new RealSwitch(in1, in2);
                 }
diff --git a/src/test/java/de/neemann/digital/integration/TestExamples.java b/src/test/java/de/neemann/digital/integration/TestExamples.java
index 3667b6eeb..fd48cf4c7 100644
--- a/src/test/java/de/neemann/digital/integration/TestExamples.java
+++ b/src/test/java/de/neemann/digital/integration/TestExamples.java
@@ -43,8 +43,8 @@ public class TestExamples extends TestCase {
      */
     public void testTestExamples() throws Exception {
         File examples = new File(Resources.getRoot(), "/dig/test");
-        assertEquals(150, new FileScanner(this::check).scan(examples));
-        assertEquals(142, testCasesInFiles);
+        assertEquals(151, new FileScanner(this::check).scan(examples));
+        assertEquals(143, testCasesInFiles);
     }
 
     /**
diff --git a/src/test/resources/dig/test/switch/const.dig b/src/test/resources/dig/test/switch/const.dig
new file mode 100644
index 000000000..10ffada4e
--- /dev/null
+++ b/src/test/resources/dig/test/switch/const.dig
@@ -0,0 +1,144 @@
+<?xml version="1.0" encoding="utf-8"?>
+<circuit>
+  <version>1</version>
+  <attributes/>
+  <visualElements>
+    <visualElement>
+      <elementName>PullDown</elementName>
+      <elementAttributes/>
+      <pos x="740" y="440"/>
+    </visualElement>
+    <visualElement>
+      <elementName>PullDown</elementName>
+      <elementAttributes/>
+      <pos x="680" y="440"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Const</elementName>
+      <elementAttributes/>
+      <pos x="660" y="320"/>
+    </visualElement>
+    <visualElement>
+      <elementName>RelayDT</elementName>
+      <elementAttributes>
+        <entry>
+          <string>rotation</string>
+          <rotation rotation="1"/>
+        </entry>
+      </elementAttributes>
+      <pos x="680" y="400"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Ground</elementName>
+      <elementAttributes/>
+      <pos x="640" y="420"/>
+    </visualElement>
+    <visualElement>
+      <elementName>In</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>A</string>
+        </entry>
+      </elementAttributes>
+      <pos x="600" y="340"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Y_1</string>
+        </entry>
+      </elementAttributes>
+      <pos x="760" y="340"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Testcase</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Testdata</string>
+          <testData>
+            <dataString>A Y_1 Y_2
+0  0   0
+1  0   1
+0  0   0
+1  0   1
+</dataString>
+          </testData>
+        </entry>
+      </elementAttributes>
+      <pos x="520" y="420"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Y_2</string>
+        </entry>
+      </elementAttributes>
+      <pos x="760" y="420"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Text</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>see issue #255</string>
+        </entry>
+      </elementAttributes>
+      <pos x="560" y="280"/>
+    </visualElement>
+  </visualElements>
+  <wires>
+    <wire>
+      <p1 x="660" y="320"/>
+      <p2 x="680" y="320"/>
+    </wire>
+    <wire>
+      <p1 x="600" y="340"/>
+      <p2 x="640" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="700" y="340"/>
+      <p2 x="740" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="740" y="340"/>
+      <p2 x="760" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="420"/>
+      <p2 x="760" y="420"/>
+    </wire>
+    <wire>
+      <p1 x="640" y="400"/>
+      <p2 x="640" y="420"/>
+    </wire>
+    <wire>
+      <p1 x="640" y="340"/>
+      <p2 x="640" y="360"/>
+    </wire>
+    <wire>
+      <p1 x="740" y="340"/>
+      <p2 x="740" y="440"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="320"/>
+      <p2 x="680" y="360"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="400"/>
+      <p2 x="680" y="420"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="420"/>
+      <p2 x="680" y="440"/>
+    </wire>
+    <wire>
+      <p1 x="700" y="340"/>
+      <p2 x="700" y="360"/>
+    </wire>
+  </wires>
+</circuit>
\ No newline at end of file