diff --git a/.travis.yml b/.travis.yml
index 0a2330c6..577b8e13 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,6 +13,8 @@ matrix:
       jdk: openjdk8
     - os: linux
       jdk: oraclejdk8
+    - os: linux
+      jdk: oraclejdk11
     - os: osx
       osx_image: xcode9.2
     - os: windows
diff --git a/brut.apktool/apktool-cli/build.gradle b/brut.apktool/apktool-cli/build.gradle
index e2bee13e..d4f0dec4 100644
--- a/brut.apktool/apktool-cli/build.gradle
+++ b/brut.apktool/apktool-cli/build.gradle
@@ -37,13 +37,24 @@ jar {
 }
 
 task cleanOutputDirectory(type: Delete) {
-    delete fileTree(dir: jar.destinationDir.getPath(), exclude: "apktool-cli-all.jar")
+    delete fileTree(dir: jar.getDestinationDirectory().getAsFile(), exclude: "apktool-cli-all.jar")
 }
 
 task proguard(type: proguard.gradle.ProGuardTask, dependsOn: shadowJar) {
-    injars shadowJar.archivePath
+    injars shadowJar.getArchiveFile()
 
-    libraryjars "${System.properties['java.home']}/lib/rt.jar"
+    // Java 9 and prior uses merged package for runtime, later uses split jmod files.
+    if (JavaVersion.current() <= JavaVersion.VERSION_1_8) {
+        libraryjars "${System.properties['java.home']}/lib/rt.jar"
+    } else {
+        libraryjars "${System.properties['java.home']}/jmods/java.base.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
+        libraryjars "${System.properties['java.home']}/jmods/java.logging.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
+        libraryjars "${System.properties['java.home']}/jmods/java.xml.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
+        libraryjars "${System.properties['java.home']}/jmods/java.desktop.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
+        libraryjars "${System.properties['java.home']}/jmods/java.sql.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
+
+        libraryjars "${System.properties['java.home']}/jmods/jdk.unsupported.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
+    }
 
     dontobfuscate
     dontoptimize
@@ -56,7 +67,9 @@ task proguard(type: proguard.gradle.ProGuardTask, dependsOn: shadowJar) {
     dontwarn 'javax.xml.xpath.**'
     dontnote '**'
 
-    def outFile = jar.destinationDir.getPath() + '/' + "apktool" + '-' + project.apktool_version + '-small' + '.' + jar.extension
+    def outPath = jar.getDestinationDirectory().getAsFile().get().toString()
+    def extension = jar.archiveExtension.get().toString()
+    def outFile = outPath + '/' + "apktool" + '-' + project.apktool_version + '-small' + '.' + extension
     outjars outFile
 }
 
diff --git a/build.gradle b/build.gradle
index d09780f9..7886ae4a 100644
--- a/build.gradle
+++ b/build.gradle
@@ -21,7 +21,7 @@ buildscript {
         options.encoding = "UTF-8"
     }
     dependencies {
-        classpath 'com.github.jengelman.gradle.plugins:shadow:5.0.0'
+        classpath 'com.github.jengelman.gradle.plugins:shadow:5.1.0'
     }
 }
 
@@ -113,7 +113,7 @@ subprojects {
                 commons_lang: 'org.apache.commons:commons-lang3:3.1',
                 guava: 'com.google.guava:guava:14.0',
                 junit: 'junit:junit:4.12',
-                proguard_gradle: 'net.sf.proguard:proguard-gradle:6.1.0',
+                proguard_gradle: 'net.sf.proguard:proguard-gradle:6.1.1',
                 snakeyaml: 'org.yaml:snakeyaml:1.18:android',
                 smali: 'org.smali:smali:2.2.7',
                 xmlpull: 'xpp3:xpp3:1.1.4c',
diff --git a/scripts/travis-ci/clean-tests.sh b/scripts/travis-ci/clean-tests.sh
index a6fc81e6..31f95b99 100755
--- a/scripts/travis-ci/clean-tests.sh
+++ b/scripts/travis-ci/clean-tests.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env sh
 
-if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then
+if [ "$TRAVIS_OS_NAME" = "windows" ]; then
     export GRADLE_OPTS=-Dorg.gradle.daemon=false
     choco install jdk8
     export PATH=$PATH:"/c/Program Files/Java/jdk1.8.0_211/bin"
diff --git a/scripts/travis-ci/run-tests.sh b/scripts/travis-ci/run-tests.sh
index 247bcee1..3467e574 100755
--- a/scripts/travis-ci/run-tests.sh
+++ b/scripts/travis-ci/run-tests.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env sh
 
-if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then
+if [ "$TRAVIS_OS_NAME" = "windows" ]; then
     export GRADLE_OPTS=-Dorg.gradle.daemon=false
     export PATH=$PATH:"/c/Program Files/Java/jdk1.8.0_211/bin"
     export JAVA_HOME="/c/Program Files/Java/jdk1.8.0_211"