diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/logging/LoggingApplicationListener.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/logging/LoggingApplicationListener.java
index ac2854b9dd..8ba14af1be 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/logging/LoggingApplicationListener.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/logging/LoggingApplicationListener.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -21,6 +21,7 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.apache.commons.logging.Log;
@@ -320,12 +321,11 @@ public class LoggingApplicationListener implements GenericApplicationListener {
 	}
 
 	protected void initializeLogLevel(LoggingSystem system, LogLevel level) {
-		List<String> loggers = LOG_LEVEL_LOGGERS.get(level);
-		if (loggers != null) {
-			for (String logger : loggers) {
-				system.setLogLevel(logger, level);
-			}
-		}
+		Optional.ofNullable(LOG_LEVEL_LOGGERS.get(level)).orElse(Collections.emptyList())
+				.stream()
+				.flatMap((logger) -> DEFAULT_GROUP_LOGGERS
+						.getOrDefault(logger, Collections.singletonList(logger)).stream())
+				.forEach((logger) -> system.setLogLevel(logger, level));
 	}
 
 	protected void setLogLevels(LoggingSystem system, Environment environment) {
diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerTests.java
index 8f5cafa3ac..03627fb478 100644
--- a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerTests.java
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -262,6 +262,21 @@ public class LoggingApplicationListenerTests {
 		assertThat(this.outputCapture.toString()).doesNotContain("testattrace");
 	}
 
+	@Test
+	public void parseDebugArgExpandGroups() {
+		addPropertiesToEnvironment(this.context, "debug");
+		this.initializer.initialize(this.context.getEnvironment(),
+				this.context.getClassLoader());
+		ch.qos.logback.classic.Logger sqlGroup = this.loggerContext
+				.getLogger("org.hibernate.SQL");
+		ch.qos.logback.classic.Logger webGroup = this.loggerContext
+				.getLogger("org.springframework.boot.actuate.endpoint.web");
+		webGroup.debug("testdebugwebgroup");
+		sqlGroup.debug("testdebugsqlgroup");
+		assertThat(this.outputCapture.toString()).contains("testdebugwebgroup");
+		assertThat(this.outputCapture.toString()).contains("testdebugsqlgroup");
+	}
+
 	@Test
 	public void parseTraceArg() {
 		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context, "trace");