diff --git a/spring-core/src/main/java/org/springframework/aot/generate/GeneratedFiles.java b/spring-core/src/main/java/org/springframework/aot/generate/GeneratedFiles.java
index 411ec8b46b..f1ae40ddf0 100644
--- a/spring-core/src/main/java/org/springframework/aot/generate/GeneratedFiles.java
+++ b/spring-core/src/main/java/org/springframework/aot/generate/GeneratedFiles.java
@@ -161,7 +161,7 @@ public interface GeneratedFiles {
 
 	private static String getClassNamePath(String className) {
 		Assert.hasLength(className, "'className' must not be empty");
-		Assert.isTrue(isJavaIdentifier(className), "'className' must be a valid identifier");
+		Assert.isTrue(isJavaIdentifier(className), "'className' " + className + " must be a valid identifier");
 		return ClassUtils.convertClassNameToResourcePath(className) + ".java";
 	}
 
diff --git a/spring-core/src/test/java/org/springframework/aot/generate/GeneratedFilesTests.java b/spring-core/src/test/java/org/springframework/aot/generate/GeneratedFilesTests.java
index 9f1f68ef30..4f13505a7b 100644
--- a/spring-core/src/test/java/org/springframework/aot/generate/GeneratedFilesTests.java
+++ b/spring-core/src/test/java/org/springframework/aot/generate/GeneratedFilesTests.java
@@ -78,7 +78,7 @@ class GeneratedFilesTests {
 		assertThatIllegalArgumentException()
 				.isThrownBy(() -> this.generatedFiles
 						.addSourceFile("com/example/HelloWorld.java", "{}"))
-				.withMessage("'className' must be a valid identifier");
+				.withMessage("'className' com/example/HelloWorld.java must be a valid identifier");
 	}
 
 	@Test