diff --git a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java
index 87ebc2a9e4..24d09c8b4f 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java
@@ -293,7 +293,7 @@ class WebMvcAutoConfigurationTests {
 		this.contextRunner.run((context) -> {
 			assertThat(context).hasSingleBean(LocaleResolver.class);
 			LocaleResolver localeResolver = context.getBean(LocaleResolver.class);
-			assertThat(((AcceptHeaderLocaleResolver) localeResolver).getDefaultLocale()).isNull();
+			assertThat(localeResolver).hasFieldOrPropertyWithValue("defaultLocale", null);
 		});
 	}