diff --git a/plugins/src/main/java/io/github/rawvoid/jaxb/plugin/NormalizeClassPlugin.java b/plugins/src/main/java/io/github/rawvoid/jaxb/plugin/NormalizeClassPlugin.java
index 36cb971..7151bab 100644
--- a/plugins/src/main/java/io/github/rawvoid/jaxb/plugin/NormalizeClassPlugin.java
+++ b/plugins/src/main/java/io/github/rawvoid/jaxb/plugin/NormalizeClassPlugin.java
@@ -74,10 +74,7 @@ private void removeEmptyDerivedClasses(Outline outline) {
             if (!isEmptyClass(implClass)) {
                 return;
             }
-            var className = implClass.name();
-            var superClassName = definedSuperClass.name();
-            if (!(className.startsWith(superClassName) || className.endsWith(superClassName)
-                || superClassName.startsWith(className) || superClassName.endsWith(className))) {
+            if (!isSimilarClassName(implClass.name(), definedSuperClass.name())) {
                 return;
             }
 
@@ -99,6 +96,13 @@ private boolean isEmptyClass(JDefinedClass definedClass) {
             && !definedClass.classes().hasNext();
     }
 
+    private boolean isSimilarClassName(String className, String superClassName) {
+        return className.startsWith(superClassName)
+            || className.endsWith(superClassName)
+            || superClassName.startsWith(className)
+            || superClassName.endsWith(className);
+    }
+
     private void clearAbstractModifier(JMods mods) {
         try {
             var flags = (int) JMODS_MODS_FIELD.get(mods);