diff --git a/src/main/java/de/neemann/digital/builder/tt2/TT2Exporter.java b/src/main/java/de/neemann/digital/builder/tt2/TT2Exporter.java
index 0d6be7f7e..2287a1874 100644
--- a/src/main/java/de/neemann/digital/builder/tt2/TT2Exporter.java
+++ b/src/main/java/de/neemann/digital/builder/tt2/TT2Exporter.java
@@ -271,6 +271,8 @@ public class TT2Exporter implements ExpressionExporter<TT2Exporter> {
             line("#$ NODES " + nodeNum + node.toString());
     }
 
+    //StateSet can not be final because its overridden. Maybe checkstyle has a bug?
+    //CHECKSTYLE.OFF: FinalClass
     private static class StateSet implements Comparable<StateSet> {
         private final int[] state;
 
@@ -332,6 +334,7 @@ public class TT2Exporter implements ExpressionExporter<TT2Exporter> {
             return sb.toString();
         }
     }
+    //CHECKSTYLE.ON: FinalClass
 
     private final class ProdInput extends StateSet {
         private ProdInput(int inputCount) {
diff --git a/src/main/java/de/neemann/digital/gui/components/CircuitComponent.java b/src/main/java/de/neemann/digital/gui/components/CircuitComponent.java
index d842f39a2..f2aeb397b 100644
--- a/src/main/java/de/neemann/digital/gui/components/CircuitComponent.java
+++ b/src/main/java/de/neemann/digital/gui/components/CircuitComponent.java
@@ -662,6 +662,8 @@ public class CircuitComponent extends JComponent implements Circuit.ChangedListe
 
     }
 
+    //MouseController can not be final because its overridden. Maybe checkstyle has a bug?
+    //CHECKSTYLE.OFF: FinalClass
     private class MouseController {
         private final Cursor mouseCursor;
 
@@ -706,6 +708,7 @@ public class CircuitComponent extends JComponent implements Circuit.ChangedListe
         public void escapePressed() {
         }
     }
+    //CHECKSTYLE.ON: FinalClass
 
     private final class MouseControllerNormal extends MouseController {
         private Vector pos;
diff --git a/src/main/java/de/neemann/digital/gui/components/EditorFactory.java b/src/main/java/de/neemann/digital/gui/components/EditorFactory.java
index 7591220b3..d85a7fd91 100644
--- a/src/main/java/de/neemann/digital/gui/components/EditorFactory.java
+++ b/src/main/java/de/neemann/digital/gui/components/EditorFactory.java
@@ -127,6 +127,7 @@ public final class EditorFactory {
         }
     }
 
+    //Checkstyle flags redundant modifiers, which are not redundant. Maybe a bug in checkstyle?
     //CHECKSTYLE.OFF: RedundantModifier
     private final static class StringEditor extends LabelEditor<String> {