diff --git a/spring-boot-dependencies/pom.xml b/spring-boot-dependencies/pom.xml
index 937aa7b8ea5..e7ffa715276 100644
--- a/spring-boot-dependencies/pom.xml
+++ b/spring-boot-dependencies/pom.xml
@@ -122,7 +122,7 @@
 		<junit.version>4.12</junit.version>
 		<liquibase.version>3.5.3</liquibase.version>
 		<log4j2.version>2.7</log4j2.version>
-		<logback.version>1.1.7</logback.version>
+		<logback.version>1.1.8</logback.version>
 		<lombok.version>1.16.10</lombok.version>
 		<mariadb.version>1.4.6</mariadb.version>
 		<mssql-jdbc.version>6.1.0.jre8</mssql-jdbc.version>
diff --git a/spring-boot/src/main/java/org/springframework/boot/logging/logback/DefaultLogbackConfiguration.java b/spring-boot/src/main/java/org/springframework/boot/logging/logback/DefaultLogbackConfiguration.java
index 1e2bcf369d5..4f92ac87549 100644
--- a/spring-boot/src/main/java/org/springframework/boot/logging/logback/DefaultLogbackConfiguration.java
+++ b/spring-boot/src/main/java/org/springframework/boot/logging/logback/DefaultLogbackConfiguration.java
@@ -26,6 +26,7 @@ import ch.qos.logback.core.ConsoleAppender;
 import ch.qos.logback.core.rolling.FixedWindowRollingPolicy;
 import ch.qos.logback.core.rolling.RollingFileAppender;
 import ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy;
+import ch.qos.logback.core.util.FileSize;
 import ch.qos.logback.core.util.OptionHelper;
 
 import org.springframework.boot.bind.RelaxedPropertyResolver;
@@ -137,7 +138,7 @@ class DefaultLogbackConfiguration {
 		config.start(rollingPolicy);
 
 		SizeBasedTriggeringPolicy<ILoggingEvent> triggeringPolicy = new SizeBasedTriggeringPolicy<ILoggingEvent>();
-		triggeringPolicy.setMaxFileSize("10MB");
+		triggeringPolicy.setMaxFileSize(FileSize.valueOf("10MB"));
 		appender.setTriggeringPolicy(triggeringPolicy);
 		config.start(triggeringPolicy);