diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/rsocket/context/RSocketPortInfoApplicationContextInitializer.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/rsocket/context/RSocketPortInfoApplicationContextInitializer.java
index 23c21156c3..aede35e677 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/rsocket/context/RSocketPortInfoApplicationContextInitializer.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/rsocket/context/RSocketPortInfoApplicationContextInitializer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -63,7 +63,9 @@ public class RSocketPortInfoApplicationContextInitializer
 
 		@Override
 		public void onApplicationEvent(RSocketServerInitializedEvent event) {
-			setPortProperty(this.applicationContext, event.getServer().address().getPort());
+			if (event.getServer().address() != null) {
+				setPortProperty(this.applicationContext, event.getServer().address().getPort());
+			}
 		}
 
 		private void setPortProperty(ApplicationContext context, int port) {
diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/rsocket/context/RSocketPortInfoApplicationContextInitializerTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/rsocket/context/RSocketPortInfoApplicationContextInitializerTests.java
new file mode 100644
index 0000000000..97f3223e0f
--- /dev/null
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/rsocket/context/RSocketPortInfoApplicationContextInitializerTests.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2012-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.boot.rsocket.context;
+
+import java.net.InetSocketAddress;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.rsocket.server.RSocketServer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+/**
+ * Tests for {@link RSocketPortInfoApplicationContextInitializer}.
+ *
+ * @author Spencer Gibb
+ * @author Andy Wilkinson
+ */
+class RSocketPortInfoApplicationContextInitializerTests {
+
+	@Test
+	void whenServerHasAddressThenInitializerSetsPortProperty() {
+		try (ConfigurableApplicationContext context = new AnnotationConfigApplicationContext(Config.class)) {
+			context.getBean(RSocketPortInfoApplicationContextInitializer.class).initialize(context);
+			RSocketServer server = mock(RSocketServer.class);
+			given(server.address()).willReturn(new InetSocketAddress(65535));
+			context.publishEvent(new RSocketServerInitializedEvent(server));
+			assertThat(context.getEnvironment().getProperty("local.rsocket.server.port")).isEqualTo("65535");
+		}
+	}
+
+	@Test
+	void whenServerHasNoAddressThenInitializerDoesNotSetPortProperty() {
+		try (ConfigurableApplicationContext context = new AnnotationConfigApplicationContext(Config.class)) {
+			context.getBean(RSocketPortInfoApplicationContextInitializer.class).initialize(context);
+			RSocketServer server = mock(RSocketServer.class);
+			context.publishEvent(new RSocketServerInitializedEvent(server));
+			verify(server).address();
+			assertThat(context.getEnvironment().getProperty("local.rsocket.server.port")).isNull();
+		}
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	static class Config {
+
+		@Bean
+		RSocketPortInfoApplicationContextInitializer rSocketPortInfoApplicationContextInitializer() {
+			return new RSocketPortInfoApplicationContextInitializer();
+		}
+
+	}
+
+}