diff --git a/.github/workflows/continuous_integration.yml b/.github/workflows/continuous_integration.yml
index 80fb732e..f5ac6440 100644
--- a/.github/workflows/continuous_integration.yml
+++ b/.github/workflows/continuous_integration.yml
@@ -23,7 +23,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           distribution: "temurin"
-          java-version: 8
+          java-version: 11
       - name: Setup gradle
         uses: gradle/actions/setup-gradle@017a9effdb900e5b5b2fddfb590a105619dca3c3 # version 4.4.2
       - name: Test
diff --git a/base/build.gradle b/base/build.gradle
index 475645d4..32c72bd5 100644
--- a/base/build.gradle
+++ b/base/build.gradle
@@ -13,11 +13,6 @@ repositories {
     mavenCentral()
 }
 
-kotlin {
-    compilerOptions {
-        jvmTarget.set(JvmTarget.fromTarget(project.findProperty("target")))
-    }
-}
 
 dependencies {
     api(libs.proguard.core)
@@ -45,14 +40,14 @@ jar {
 // Early access automatic downloads are not yet supported:
 // https://github.com/gradle/gradle/issues/14814
 // But it will work if e.g. Java N-ea is pre-installed
-def javaVersionsForTest = 9..23
+def javaVersionsForTest = 12..25
 
 test {
     useJUnitPlatform()
 }
 
 def testAllJavaVersion = tasks.register("testAllJavaVersions"){ testAllTask ->
-    dependsOn(test) // the usual test runs on Java 8
+    dependsOn(test) // the usual test runs on Java 11
 }
 
 javaVersionsForTest.each {version ->
diff --git a/base/src/test/kotlin/proguard/Java19RecordPatternTest.kt b/base/src/test/kotlin/proguard/Java19RecordPatternTest.kt
index 01519bcc..1de7bc15 100644
--- a/base/src/test/kotlin/proguard/Java19RecordPatternTest.kt
+++ b/base/src/test/kotlin/proguard/Java19RecordPatternTest.kt
@@ -4,10 +4,10 @@ import io.kotest.core.spec.style.FreeSpec
 import io.kotest.matchers.shouldNotBe
 import proguard.testutils.ClassPoolBuilder
 import proguard.testutils.JavaSource
-import testutils.RequiresJavaVersion
+import testutils.RequiresJavaExtension
 
-@RequiresJavaVersion(19, 19)
 class Java19RecordPatternTest : FreeSpec({
+    extension(RequiresJavaExtension(from = 19, to = 19))
     "Given a class with Java record pattern" - {
         val (programClassPool, _) =
             ClassPoolBuilder.fromSource(
diff --git a/base/src/test/kotlin/proguard/Java20RecordPatternTest.kt b/base/src/test/kotlin/proguard/Java20RecordPatternTest.kt
index 4e1750e4..05f43220 100644
--- a/base/src/test/kotlin/proguard/Java20RecordPatternTest.kt
+++ b/base/src/test/kotlin/proguard/Java20RecordPatternTest.kt
@@ -4,10 +4,10 @@ import io.kotest.core.spec.style.FreeSpec
 import io.kotest.matchers.shouldNotBe
 import proguard.testutils.ClassPoolBuilder
 import proguard.testutils.JavaSource
-import testutils.RequiresJavaVersion
+import testutils.RequiresJavaExtension
 
-@RequiresJavaVersion(20, 20)
 class Java20RecordPatternTest : FreeSpec({
+    extension(RequiresJavaExtension(from = 20, to = 20))
     "Given a class with Java record pattern" - {
         val (programClassPool, _) =
             ClassPoolBuilder.fromSource(
diff --git a/base/src/test/kotlin/proguard/optimize/peephole/MethodInlinerJava9Test.kt b/base/src/test/kotlin/proguard/optimize/peephole/MethodInlinerJava9Test.kt
index e19a9fe4..e131c368 100644
--- a/base/src/test/kotlin/proguard/optimize/peephole/MethodInlinerJava9Test.kt
+++ b/base/src/test/kotlin/proguard/optimize/peephole/MethodInlinerJava9Test.kt
@@ -16,9 +16,7 @@ import proguard.optimize.info.ProgramClassOptimizationInfoSetter
 import proguard.optimize.info.ProgramMemberOptimizationInfoSetter
 import proguard.testutils.ClassPoolBuilder
 import proguard.testutils.JavaSource
-import testutils.RequiresJavaVersion
 
-@RequiresJavaVersion(9)
 class MethodInlinerJava9Test : FreeSpec({
     isolationMode = IsolationMode.InstancePerTest
 
diff --git a/base/src/test/kotlin/proguard/shrink/UsageMarkerTest.kt b/base/src/test/kotlin/proguard/shrink/UsageMarkerTest.kt
index df4bf4eb..56ee417b 100644
--- a/base/src/test/kotlin/proguard/shrink/UsageMarkerTest.kt
+++ b/base/src/test/kotlin/proguard/shrink/UsageMarkerTest.kt
@@ -17,9 +17,10 @@ import proguard.classfile.visitor.MultiClassVisitor
 import proguard.resources.file.ResourceFilePool
 import proguard.testutils.ClassPoolBuilder
 import proguard.testutils.JavaSource
-import proguard.testutils.RequiresJavaVersion
+import testutils.RequiresJavaExtension
 import proguard.util.ProcessingFlagSetter
 import proguard.util.ProcessingFlags.DONT_SHRINK
+import testutils.currentJavaVersion
 
 class UsageMarkerTest : BehaviorSpec({
     Given("A class pool with interfaces only referenced through annotations") {
@@ -89,8 +90,8 @@ class UsageMarkerTest : BehaviorSpec({
 
 })
 
-@RequiresJavaVersion(15)
 class Java15UsageMarkerTest : BehaviorSpec({
+    extension(RequiresJavaExtension(from = 15))
     // Regression test for https://github.com/Guardsquare/proguard/issues/501
     Given("A class pool containing a sealed interface extending another sealed interface, and final classes implementing both") {
         val (programClassPool, _) = ClassPoolBuilder.fromSource(
@@ -169,7 +170,7 @@ class Java15UsageMarkerTest : BehaviorSpec({
                 }
 
             """.trimIndent()
-            ), javacArguments = listOf("--enable-preview", "--release", "15"),
+            ), javacArguments = if (currentJavaVersion in 15..16) listOf("--enable-preview", "--release", "$currentJavaVersion") else emptyList(),
         )
         val animal = programClassPool.getClass("sample/Animal")
 
diff --git a/base/src/test/kotlin/testutils/TestConfig.kt b/base/src/test/kotlin/testutils/TestConfig.kt
index c50862fe..09898e58 100644
--- a/base/src/test/kotlin/testutils/TestConfig.kt
+++ b/base/src/test/kotlin/testutils/TestConfig.kt
@@ -8,32 +8,21 @@
 package testutils
 
 import io.kotest.core.config.AbstractProjectConfig
-import io.kotest.core.extensions.Extension
-import io.kotest.core.filter.SpecFilter
-import io.kotest.core.filter.SpecFilterResult
-import io.kotest.core.filter.SpecFilterResult.Exclude
-import io.kotest.core.filter.SpecFilterResult.Include
-import kotlin.reflect.KClass
-import kotlin.reflect.full.findAnnotation
+import io.kotest.core.extensions.SpecExtension
+import io.kotest.core.spec.Spec
+import proguard.testutils.currentJavaVersion
+
 
 @Suppress("UNUSED")
-object TestConfig : AbstractProjectConfig() {
-    override fun extensions(): List<Extension> {
-        return listOf(RequiresJavaVersionAnnotationFilter())
-    }
-}
+object TestConfig : AbstractProjectConfig() {}
 
-class RequiresJavaVersionAnnotationFilter : SpecFilter {
-    override fun filter(kclass: KClass<*>): SpecFilterResult =
-        if (with(kclass.findAnnotation<RequiresJavaVersion>()) {
-                (this == null || (currentJavaVersion >= this.from && currentJavaVersion <= this.to))
-            }
-        ) {
-            Include
-        } else {
-            Exclude("Required Java version is not in range.")
+class RequiresJavaExtension(private val from: Int, private val to: Int = Int.MAX_VALUE) : SpecExtension {
+    override suspend fun intercept(
+        spec: Spec,
+        execute: suspend (Spec) -> Unit,
+    ) {
+        if (currentJavaVersion in from..to) {
+            execute(spec)
         }
+    }
 }
-
-@Target(AnnotationTarget.CLASS)
-annotation class RequiresJavaVersion(val from: Int, val to: Int = Int.MAX_VALUE)
diff --git a/build.gradle b/build.gradle
index 26d1e2c1..36bee48e 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,3 +1,7 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompilationTask
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+import org.jetbrains.kotlin.gradle.dsl.KotlinVersion
 plugins {
     id 'distribution'
     id 'io.github.gradle-nexus.publish-plugin'
@@ -108,11 +112,21 @@ allprojects { Project project ->
                 }
                 java {
                     toolchain {
-                        languageVersion.set(JavaLanguageVersion.of(8))
+                        languageVersion.set(JavaLanguageVersion.of(11))
                     }
                     withJavadocJar()
                     withSourcesJar()
                 }
+                tasks.withType(JavaCompile).configureEach {
+                    if (!it.name.contains("Test")) {
+                        options.release = 8
+                    }
+                }
+                tasks.withType(KotlinCompile).configureEach {
+                    if (!it.name.contains("Test")) {
+                        it.compilerOptions.jvmTarget = JvmTarget.JVM_1_8
+                    }
+                }
                 publishing {
                     publications {
                         named(project.name) {
diff --git a/gradle-plugin/build.gradle b/gradle-plugin/build.gradle
index 9540df5b..a016efff 100644
--- a/gradle-plugin/build.gradle
+++ b/gradle-plugin/build.gradle
@@ -23,12 +23,6 @@ gradlePlugin {
     }
 }
 
-kotlin {
-    compilerOptions {
-        jvmTarget.set(JvmTarget.fromTarget(project.findProperty("target")))
-    }
-}
-
 configurations {
     fatJar.extendsFrom(compile)
 }
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index a2307647..c0a220dd 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -5,7 +5,7 @@ commons = "2.18.0"
 gson = "2.11.0"
 javaSemver = "0.10.2"
 json = "20231013"
-kotest = "5.9.1"
+kotest = "6.1.4"
 kotlin = "2.2.0"
 log4j = "2.25.3"
 mockk = "1.13.13"
@@ -23,7 +23,6 @@ kotest-runner-jvm = { group = "io.kotest", name = "kotest-runner-junit5-jvm", ve
 kotest-assertions-jvm = { group = "io.kotest", name = "kotest-assertions-core-jvm", version.ref = "kotest" }
 kotest-propery-jvm = { group = "io.kotest", name = "kotest-property-jvm", version.ref = "kotest" }
 kotlin-compile-testing = { module = "dev.zacsweers.kctfork:core", version.ref = "kotlin-compile-testing" }
-kotest-framework-datatest = { group = "io.kotest", name = "kotest-framework-datatest", version.ref = "kotest" }
 kotlin-stdlib = { group = "org.jetbrains.kotlin", name = "kotlin-stdlib", version.ref = "kotlin" }
 kotlin-reflect = { group = "org.jetbrains.kotlin", name = "kotlin-reflect", version.ref = "kotlin" }
 log4j-api =  { group = "org.apache.logging.log4j", name = "log4j-api", version.ref = "log4j" }
@@ -33,7 +32,7 @@ proguard-core = { group = "com.guardsquare", name = "proguard-core", version.ref
 
 [bundles]
 log4j = ["log4j-api","log4j-core"]
-kotest = ["kotest-assertions-jvm", "kotest-runner-jvm", "kotest-propery-jvm", "kotest-framework-datatest"]
+kotest = ["kotest-assertions-jvm", "kotest-runner-jvm", "kotest-propery-jvm"]
 
 [plugins]
 kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }