diff --git a/smoke-test/spring-boot-smoke-test-webflux/build.gradle b/smoke-test/spring-boot-smoke-test-webflux/build.gradle
index c90977d2a5d..be6451fccda 100644
--- a/smoke-test/spring-boot-smoke-test-webflux/build.gradle
+++ b/smoke-test/spring-boot-smoke-test-webflux/build.gradle
@@ -30,3 +30,7 @@ dependencies {
 	testImplementation(project(":starter:spring-boot-starter-webflux-test"))
 	testImplementation("io.projectreactor:reactor-test")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}
diff --git a/smoke-test/spring-boot-smoke-test-webflux/src/test/java/smoketest/webflux/SampleWebFluxApplicationIntegrationTests.java b/smoke-test/spring-boot-smoke-test-webflux/src/test/java/smoketest/webflux/SampleWebFluxApplicationIntegrationTests.java
index 30015b5d2c7..b1fb9c0f04c 100644
--- a/smoke-test/spring-boot-smoke-test-webflux/src/test/java/smoketest/webflux/SampleWebFluxApplicationIntegrationTests.java
+++ b/smoke-test/spring-boot-smoke-test-webflux/src/test/java/smoketest/webflux/SampleWebFluxApplicationIntegrationTests.java
@@ -16,6 +16,9 @@
 
 package smoketest.webflux;
 
+import java.util.function.Consumer;
+
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
 
@@ -77,6 +80,7 @@ class SampleWebFluxApplicationIntegrationTests {
 
 	@Test
 	void templated404ErrorPage() {
+		Consumer<@Nullable String> test = (body) -> assertThat(body).isEqualToNormalizingNewlines("404 page\n");
 		this.webClient.get()
 			.uri("/404")
 			.accept(MediaType.TEXT_HTML)
@@ -84,11 +88,12 @@ class SampleWebFluxApplicationIntegrationTests {
 			.expectStatus()
 			.isNotFound()
 			.expectBody(String.class)
-			.value((body) -> assertThat(body).isEqualToNormalizingNewlines("404 page\n"));
+			.value(test);
 	}
 
 	@Test
 	void templated4xxErrorPage() {
+		Consumer<@Nullable String> test = (body) -> assertThat(body).isEqualToNormalizingNewlines("4xx page\n");
 		this.webClient.get()
 			.uri("/bad-request")
 			.accept(MediaType.TEXT_HTML)
@@ -96,11 +101,13 @@ class SampleWebFluxApplicationIntegrationTests {
 			.expectStatus()
 			.isBadRequest()
 			.expectBody(String.class)
-			.value((body) -> assertThat(body).isEqualToNormalizingNewlines("4xx page\n"));
+			.value(test);
 	}
 
 	@Test
 	void htmlErrorPage() {
+		Consumer<@Nullable String> test = (body) -> assertThat(body).contains("status: 500")
+			.contains("message: Expected!");
 		this.webClient.get()
 			.uri("/five-hundred")
 			.accept(MediaType.TEXT_HTML)
@@ -108,7 +115,7 @@ class SampleWebFluxApplicationIntegrationTests {
 			.expectStatus()
 			.isEqualTo(HttpStatus.INTERNAL_SERVER_ERROR)
 			.expectBody(String.class)
-			.value((body) -> assertThat(body).contains("status: 500").contains("message: Expected!"));
+			.value(test);
 	}
 
 }
diff --git a/smoke-test/spring-boot-smoke-test-webflux/src/test/java/smoketest/webflux/SampleWebFluxApplicationTests.java b/smoke-test/spring-boot-smoke-test-webflux/src/test/java/smoketest/webflux/SampleWebFluxApplicationTests.java
index 17d1cf8c08c..2d33621c0d9 100644
--- a/smoke-test/spring-boot-smoke-test-webflux/src/test/java/smoketest/webflux/SampleWebFluxApplicationTests.java
+++ b/smoke-test/spring-boot-smoke-test-webflux/src/test/java/smoketest/webflux/SampleWebFluxApplicationTests.java
@@ -17,7 +17,9 @@
 package smoketest.webflux;
 
 import java.util.Map;
+import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
 
@@ -61,6 +63,8 @@ class SampleWebFluxApplicationTests {
 
 	@Test
 	void testBadRequest() {
+		Consumer<@Nullable Map<String, Object>> test = (content) -> assertThat(content).containsEntry("path",
+				"/bad-request");
 		this.webClient.get()
 			.uri("/bad-request")
 			.accept(MediaType.APPLICATION_JSON)
@@ -68,11 +72,13 @@ class SampleWebFluxApplicationTests {
 			.expectStatus()
 			.isBadRequest()
 			.expectBody(MAP_TYPE)
-			.value((content) -> assertThat(content).containsEntry("path", "/bad-request"));
+			.value(test);
 	}
 
 	@Test
 	void testServerError() {
+		Consumer<@Nullable Map<String, Object>> test = (content) -> assertThat(content).containsEntry("path",
+				"/five-hundred");
 		this.webClient.get()
 			.uri("/five-hundred")
 			.accept(MediaType.APPLICATION_JSON)
@@ -80,7 +86,7 @@ class SampleWebFluxApplicationTests {
 			.expectStatus()
 			.isEqualTo(HttpStatus.INTERNAL_SERVER_ERROR)
 			.expectBody(MAP_TYPE)
-			.value((content) -> assertThat(content).containsEntry("path", "/five-hundred"));
+			.value(test);
 	}
 
 }