diff --git a/pom.xml b/pom.xml
index dc1f1144c..a35b583d1 100644
--- a/pom.xml
+++ b/pom.xml
@@ -50,6 +50,10 @@
                     </reportSet>
                 </reportSets>
             </plugin>
+            <plugin>
+                <artifactId>maven-pmd-plugin</artifactId>
+                <version>3.6</version>
+            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
diff --git a/src/main/java/de/neemann/digital/analyse/DetermineJKStateMachine.java b/src/main/java/de/neemann/digital/analyse/DetermineJKStateMachine.java
index 1131f7ea3..e68a3dc03 100644
--- a/src/main/java/de/neemann/digital/analyse/DetermineJKStateMachine.java
+++ b/src/main/java/de/neemann/digital/analyse/DetermineJKStateMachine.java
@@ -31,7 +31,7 @@ public class DetermineJKStateMachine {
      * @throws FormatterException  FormatterException
      */
     public DetermineJKStateMachine(String name, Expression e) throws ExpressionException, FormatterException {
-        String notName = FormatToExpression.FORMATTER_UNICODE.format(Not.not(new Variable(name)));
+        String notName = FormatToExpression.FORMATTER_UNICODE.format(not(new Variable(name)));
 
         boolean wasK = false;
         boolean wasJ = false;