diff --git a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitProperties.java b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitProperties.java
index b17c1639886..aba11e463c0 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitProperties.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitProperties.java
@@ -1127,17 +1127,20 @@ public class RabbitProperties {
 		}
 
 		private String parseUsernameAndPassword(String input) {
-			if (input.contains("@")) {
-				String[] split = StringUtils.split(input, "@");
-				String creds = split[0];
-				input = split[1];
-				split = StringUtils.split(creds, ":");
-				this.username = split[0];
-				if (split.length > 0) {
-					this.password = split[1];
-				}
+			String[] splitInput = StringUtils.split(input, "@");
+			if (splitInput == null) {
+				return input;
 			}
-			return input;
+			String credentials = splitInput[0];
+			String[] splitCredentials = StringUtils.split(credentials, ":");
+			if (splitCredentials == null) {
+				this.username = credentials;
+			}
+			else {
+				this.username = splitCredentials[0];
+				this.password = splitCredentials[1];
+			}
+			return splitInput[1];
 		}
 
 		private String parseVirtualHost(String input) {
diff --git a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/amqp/RabbitPropertiesTests.java b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/amqp/RabbitPropertiesTests.java
index 9dd47e9fce9..569370b2ac6 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/amqp/RabbitPropertiesTests.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/amqp/RabbitPropertiesTests.java
@@ -331,4 +331,11 @@ class RabbitPropertiesTests {
 		assertThat(container).hasFieldOrPropertyWithValue("deBatchingEnabled", direct.isDeBatchingEnabled());
 	}
 
+	@Test
+	void determineUsernameWithoutPassword() {
+		this.properties.setAddresses("user@rabbit1.example.com:1234/alpha");
+		assertThat(this.properties.determineUsername()).isEqualTo("user");
+		assertThat(this.properties.determinePassword()).isEqualTo("guest");
+	}
+
 }