diff --git a/smoke-test/spring-boot-smoke-test-liquibase/build.gradle b/smoke-test/spring-boot-smoke-test-liquibase/build.gradle
index c15cb7d1ba9..a0f8f64ce47 100644
--- a/smoke-test/spring-boot-smoke-test-liquibase/build.gradle
+++ b/smoke-test/spring-boot-smoke-test-liquibase/build.gradle
@@ -29,3 +29,7 @@ dependencies {
 
 	testImplementation(project(":starter:spring-boot-starter-test"))
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}
diff --git a/smoke-test/spring-boot-smoke-test-liquibase/src/test/java/smoketest/liquibase/SampleLiquibaseApplicationTests.java b/smoke-test/spring-boot-smoke-test-liquibase/src/test/java/smoketest/liquibase/SampleLiquibaseApplicationTests.java
index 54085c278ca..0c8a18e6148 100644
--- a/smoke-test/spring-boot-smoke-test-liquibase/src/test/java/smoketest/liquibase/SampleLiquibaseApplicationTests.java
+++ b/smoke-test/spring-boot-smoke-test-liquibase/src/test/java/smoketest/liquibase/SampleLiquibaseApplicationTests.java
@@ -69,7 +69,10 @@ class SampleLiquibaseApplicationTests {
 		};
 		if (nested.contains(ConnectException.class)) {
 			Throwable root = nested.getRootCause();
-			return root.getMessage().contains("Connection refused");
+			assertThat(root).isNotNull();
+			String message = root.getMessage();
+			assertThat(message).isNotNull();
+			return message.contains("Connection refused");
 		}
 		return false;
 	}