diff --git a/spring-boot-project/spring-boot/src/main/kotlin/org/springframework/boot/SpringApplicationExtensions.kt b/spring-boot-project/spring-boot/src/main/kotlin/org/springframework/boot/SpringApplicationExtensions.kt
index 142838bfd4..e4f9840a8b 100644
--- a/spring-boot-project/spring-boot/src/main/kotlin/org/springframework/boot/SpringApplicationExtensions.kt
+++ b/spring-boot-project/spring-boot/src/main/kotlin/org/springframework/boot/SpringApplicationExtensions.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,14 +55,14 @@ inline fun <reified T : Any> runApplication(vararg args: String, init: SpringApp
  */
 inline fun <reified T : Any> fromApplication(): SpringApplication.Augmented {
 	val type = T::class
-	val ktClassName = type.qualifiedName + "Kt"
+	val ktClassName = "${type.qualifiedName}Kt"
 	try {
 		val ktClass = ClassUtils.resolveClassName(ktClassName, type.java.classLoader)
 		val mainMethod = ReflectionUtils.findMethod(ktClass, "main", Array<String>::class.java)
 		Assert.notNull(mainMethod, "Unable to find main method")
 		return SpringApplication.from { ReflectionUtils.invokeMethod(mainMethod!!, null, it) }
 	} catch (ex: Exception) {
-		throw IllegalStateException("Unable to use 'fromApplication' with " + type.qualifiedName)
+		throw IllegalStateException("Unable to use 'fromApplication' with ${type.qualifiedName}")
 	}
 }