diff --git a/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/LoggersMvcEndpoint.java b/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/LoggersMvcEndpoint.java
index 9fa355aba3c..af991d0f55e 100644
--- a/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/LoggersMvcEndpoint.java
+++ b/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/LoggersMvcEndpoint.java
@@ -35,6 +35,7 @@ import org.springframework.web.bind.annotation.ResponseBody;
  * Adapter to expose {@link LoggersEndpoint} as an {@link MvcEndpoint}.
  *
  * @author Ben Hale
+ * @author Kazuki Shimizu
  * @since 1.5.0
  */
 @ConfigurationProperties(prefix = "endpoints.loggers")
@@ -71,7 +72,8 @@ public class LoggersMvcEndpoint extends EndpointMvcAdapter {
 			return getDisabledResponse();
 		}
 		String level = configuration.get("configuredLevel");
-		this.delegate.setLogLevel(name, level == null ? null : LogLevel.valueOf(level));
+		LogLevel logLevel = level == null ? null : LogLevel.valueOf(level.toUpperCase());
+		this.delegate.setLogLevel(name, logLevel);
 		return HttpEntity.EMPTY;
 	}
 
diff --git a/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/LoggersMvcEndpointTests.java b/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/LoggersMvcEndpointTests.java
index 5b9edcf5d67..63eea415be5 100644
--- a/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/LoggersMvcEndpointTests.java
+++ b/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/LoggersMvcEndpointTests.java
@@ -131,7 +131,7 @@ public class LoggersMvcEndpointTests {
 	@Test
 	public void setLoggerShouldSetLogLevel() throws Exception {
 		this.mvc.perform(post("/loggers/ROOT").contentType(MediaType.APPLICATION_JSON)
-				.content("{\"configuredLevel\":\"DEBUG\"}")).andExpect(status().isOk());
+				.content("{\"configuredLevel\":\"debug\"}")).andExpect(status().isOk());
 		verify(this.loggingSystem).setLogLevel("ROOT", LogLevel.DEBUG);
 	}