diff --git a/.github/workflows/ant.yml b/.github/workflows/ant.yml
index a216ebba60..d28dc1352b 100644
--- a/.github/workflows/ant.yml
+++ b/.github/workflows/ant.yml
@@ -183,3 +183,32 @@ jobs:
         
       - name: Compile in container
         run: docker run --entrypoint="" -v $(pwd)/lombok.jar:/workspace/lombok.jar $IMAGE_NAME /bin/bash -c "cd classpath; ${{ matrix.tool.cmd }}"
+  
+  manual-tests:
+    runs-on: ubuntu-24.04
+    needs: build
+    strategy: 
+      matrix: 
+        jdk: [8, 11, 17, 21, 23]
+        dir: [compileTests]
+      fail-fast: false
+    
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        
+      - name: Set up JDK ${{ matrix.jdk }}
+        uses: actions/setup-java@v4
+        with:
+          java-version: ${{ matrix.jdk }}
+          distribution: 'zulu'
+          
+      - uses: actions/download-artifact@v4
+        with:
+          name: lombok.jar
+          path: dist
+          
+      - name: Run tests
+        working-directory: ./test/manual/${{ matrix.dir }}/
+        run: ./runTests.sh
+
diff --git a/src/core/lombok/javac/handlers/HandleUtilityClass.java b/src/core/lombok/javac/handlers/HandleUtilityClass.java
index b20aee3ae6..bc171b8f89 100644
--- a/src/core/lombok/javac/handlers/HandleUtilityClass.java
+++ b/src/core/lombok/javac/handlers/HandleUtilityClass.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015-2021 The Project Lombok Authors.
+ * Copyright (C) 2015-2024 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -107,7 +107,7 @@ private void changeModifiersAndGenerateConstructor(JavacNode typeNode, JavacNode
 			if ((typeDecl.mods.flags & (Flags.INTERFACE | Flags.ANNOTATION)) != 0) markStatic = false;
 		}
 		
-		if (markStatic) classDecl.mods.flags |= Flags.STATIC;
+		if (markStatic) markClassAsStatic(classDecl);
 		
 		for (JavacNode element : typeNode.down()) {
 			if (element.getKind() == Kind.FIELD) {
@@ -125,21 +125,23 @@ private void changeModifiersAndGenerateConstructor(JavacNode typeNode, JavacNode
 				
 				methodDecl.mods.flags |= Flags.STATIC;
 			} else if (element.getKind() == Kind.TYPE) {
-				JCClassDecl innerClassDecl = (JCClassDecl) element.get();
-				innerClassDecl.mods.flags |= Flags.STATIC;
-				ClassSymbol innerClassSymbol = innerClassDecl.sym;
-				if (innerClassSymbol != null) {
-					if (innerClassSymbol.type instanceof ClassType) {
-						((ClassType) innerClassSymbol.type).setEnclosingType(Type.noType);
-					}
-					innerClassSymbol.erasure_field = null;
-				}
+				markClassAsStatic((JCClassDecl) element.get());
 			}
 		}
 		
 		if (makeConstructor) createPrivateDefaultConstructor(typeNode);
 	}
 	
+	private void markClassAsStatic(JCClassDecl classDecl) {
+		classDecl.mods.flags |= Flags.STATIC; // maybe Flags.NOOUTERTHIS too?
+		ClassSymbol innerClassSymbol = classDecl.sym;
+		if (innerClassSymbol != null && innerClassSymbol.type instanceof ClassType) {
+			ClassType classType = (ClassType) innerClassSymbol.type;
+			classType.setEnclosingType(Type.noType);
+			innerClassSymbol.erasure_field = null;
+		}
+	}
+	
 	private void createPrivateDefaultConstructor(JavacNode typeNode) {
 		JavacTreeMaker maker = typeNode.getTreeMaker();
 		JCModifiers mods = maker.Modifiers(Flags.PRIVATE, List.<JCAnnotation>nil());
diff --git a/test/manual/compileTests/.gitignore b/test/manual/compileTests/.gitignore
new file mode 100644
index 0000000000..e2e7327cde
--- /dev/null
+++ b/test/manual/compileTests/.gitignore
@@ -0,0 +1 @@
+/out
diff --git a/test/manual/compileTests/runTests.sh b/test/manual/compileTests/runTests.sh
new file mode 100755
index 0000000000..1b129920e1
--- /dev/null
+++ b/test/manual/compileTests/runTests.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+set -e
+echo 'This will compile a selection of files in test/transform/resource/before. If the compilation works without error, lombok is working as designed.'
+
+mkdir -p out/
+
+# list of files to iterate over
+FILES="UtilityClassInner.java"
+BASE_PATH="../../../test/transform/resource/before"
+LOMBOK_JAR="../../../dist/lombok.jar"
+
+# compile all files in list
+for f in $FILES
+do
+  
+  echo "Compiling $f"
+  javac -processorpath $LOMBOK_JAR -cp $LOMBOK_JAR -d out/ $BASE_PATH/$f
+done
+
+rm -rf out/
diff --git a/test/transform/resource/after-delombok/UtilityClassInner.java b/test/transform/resource/after-delombok/UtilityClassInner.java
index 4c4c674377..cd91bc2d7c 100644
--- a/test/transform/resource/after-delombok/UtilityClassInner.java
+++ b/test/transform/resource/after-delombok/UtilityClassInner.java
@@ -1,5 +1,6 @@
+@java.lang.SuppressWarnings("serial")
 class UtilityClassInner {
-	static final class UtilClass {
+	static final class UtilClass implements java.io.Serializable {
 		@java.lang.SuppressWarnings("all")
 		@lombok.Generated
 		private UtilClass() {
diff --git a/test/transform/resource/after-ecj/UtilityClassInner.java b/test/transform/resource/after-ecj/UtilityClassInner.java
index 9086367cf8..31bd396c41 100644
--- a/test/transform/resource/after-ecj/UtilityClassInner.java
+++ b/test/transform/resource/after-ecj/UtilityClassInner.java
@@ -1,5 +1,5 @@
-class UtilityClassInner {
-  static final @lombok.experimental.UtilityClass class UtilClass {
+@java.lang.SuppressWarnings("serial") class UtilityClassInner {
+  static final @lombok.experimental.UtilityClass class UtilClass implements java.io.Serializable {
     private @java.lang.SuppressWarnings("all") @lombok.Generated UtilClass() {
       super();
       throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
diff --git a/test/transform/resource/before/UtilityClassInner.java b/test/transform/resource/before/UtilityClassInner.java
index ccb0101b17..8fd3a9e7ff 100644
--- a/test/transform/resource/before/UtilityClassInner.java
+++ b/test/transform/resource/before/UtilityClassInner.java
@@ -1,4 +1,5 @@
+@java.lang.SuppressWarnings("serial")
 class UtilityClassInner {
 	@lombok.experimental.UtilityClass
-	class UtilClass {}
+	class UtilClass implements java.io.Serializable {}
 }
\ No newline at end of file