diff --git a/build.gradle b/build.gradle
index 78a7267..c73b60c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -68,8 +68,6 @@ allprojects {
     description = "Stateless OpenPGP Protocol API for Java"
     version = shortVersion
 
-    sourceCompatibility = javaSourceCompatibility
-
     repositories {
         mavenCentral()
     }
@@ -78,6 +76,13 @@ allprojects {
     tasks.withType(AbstractArchiveTask) {
         preserveFileTimestamps = false
         reproducibleFileOrder = true
+
+        dirMode = 0755
+        fileMode = 0644
+    }
+
+    kotlin {
+        jvmToolchain(javaSourceCompatibility)
     }
 
     // Compatibility of default implementations in kotlin interfaces with Java implementations.
@@ -112,7 +117,7 @@ allprojects {
     }
 
     jacoco {
-        toolVersion = "0.8.7"
+        toolVersion = "0.8.8"
     }
 
     jacocoTestReport {
@@ -120,7 +125,7 @@ allprojects {
         sourceDirectories.setFrom(project.files(sourceSets.main.allSource.srcDirs))
         classDirectories.setFrom(project.files(sourceSets.main.output))
         reports {
-            xml.enabled true
+            xml.required = true
         }
     }
 
@@ -138,15 +143,15 @@ subprojects {
     apply plugin: 'signing'
 
     task sourcesJar(type: Jar, dependsOn: classes) {
-        classifier = 'sources'
+        archiveClassifier = 'sources'
         from sourceSets.main.allSource
     }
     task javadocJar(type: Jar, dependsOn: javadoc) {
-        classifier = 'javadoc'
+        archiveClassifier = 'javadoc'
         from javadoc.destinationDir
     }
     task testsJar(type: Jar, dependsOn: testClasses) {
-        classifier = 'tests'
+        archiveClassifier = 'tests'
         from sourceSets.test.output
     }
 
@@ -243,7 +248,7 @@ task jacocoRootReport(type: JacocoReport) {
     classDirectories.setFrom(files(subprojects.sourceSets.main.output))
     executionData.setFrom(files(subprojects.jacocoTestReport.executionData))
     reports {
-        xml.enabled true
+        xml.required = true
         xml.destination file("${buildDir}/reports/jacoco/test/jacocoTestReport.xml")
     }
     // We could remove the following setOnlyIf line, but then
@@ -254,10 +259,6 @@ task jacocoRootReport(type: JacocoReport) {
 }
 
 task javadocAll(type: Javadoc) {
-    def currentJavaVersion = JavaVersion.current()
-    if (currentJavaVersion.compareTo(JavaVersion.VERSION_1_9) >= 0) {
-        options.addStringOption("-release", "8");
-    }
     source subprojects.collect {project ->
         project.sourceSets.main.allJava }
     destinationDir = new File(buildDir, 'javadoc')
diff --git a/external-sop/src/main/kotlin/sop/external/operation/UpdateKeyExternal.kt b/external-sop/src/main/kotlin/sop/external/operation/UpdateKeyExternal.kt
index 99df15e..b84f452 100644
--- a/external-sop/src/main/kotlin/sop/external/operation/UpdateKeyExternal.kt
+++ b/external-sop/src/main/kotlin/sop/external/operation/UpdateKeyExternal.kt
@@ -21,7 +21,9 @@ class UpdateKeyExternal(binary: String, environment: Properties) : UpdateKey {
 
     override fun signingOnly(): UpdateKey = apply { commandList.add("--signing-only") }
 
-    override fun noAddedCapabilities(): UpdateKey = apply { commandList.add("--no-added-capabilities") }
+    override fun noAddedCapabilities(): UpdateKey = apply {
+        commandList.add("--no-added-capabilities")
+    }
 
     override fun withKeyPassword(password: ByteArray): UpdateKey = apply {
         commandList.add("--with-key-password=@ENV:KEY_PASSWORD_$argCount")
diff --git a/sop-java/src/main/kotlin/sop/operation/UpdateKey.kt b/sop-java/src/main/kotlin/sop/operation/UpdateKey.kt
index 9a31310..1226ed5 100644
--- a/sop-java/src/main/kotlin/sop/operation/UpdateKey.kt
+++ b/sop-java/src/main/kotlin/sop/operation/UpdateKey.kt
@@ -20,14 +20,14 @@ interface UpdateKey {
     fun noArmor(): UpdateKey
 
     /**
-     * Allow key to be used for signing only.
-     * If this option is not present, the operation may add a new, encryption-capable component key.
+     * Allow key to be used for signing only. If this option is not present, the operation may add a
+     * new, encryption-capable component key.
      */
     @Throws(SOPGPException.UnsupportedOption::class) fun signingOnly(): UpdateKey
 
     /**
-     * Do not allow adding new capabilities to the key.
-     * If this option is not present, the operation may add support for new capabilities to the key.
+     * Do not allow adding new capabilities to the key. If this option is not present, the operation
+     * may add support for new capabilities to the key.
      */
     @Throws(SOPGPException.UnsupportedOption::class) fun noAddedCapabilities(): UpdateKey
 
diff --git a/version.gradle b/version.gradle
index f98a318..c757e1e 100644
--- a/version.gradle
+++ b/version.gradle
@@ -7,7 +7,7 @@ allprojects {
         shortVersion = '11.0.0'
         isSnapshot = true
         minAndroidSdk = 10
-        javaSourceCompatibility = 1.8
+        javaSourceCompatibility = 11
         gsonVersion = '2.10.1'
         jsrVersion = '3.0.2'
         junitVersion = '5.8.2'