diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 4175002..51ba0a8 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -11,8 +11,8 @@ jobs:
       - name: Setup Java
         uses: actions/setup-java@v4
         with:
-          distribution: adopt
-          java-version: 11
+          distribution: temurin
+          java-version: 21
           cache: gradle
 
       - name: Test
diff --git a/.github/workflows/spotless.yml b/.github/workflows/spotless.yml
index 9c86075..4f0654c 100644
--- a/.github/workflows/spotless.yml
+++ b/.github/workflows/spotless.yml
@@ -11,8 +11,8 @@ jobs:
       - name: Setup Java
         uses: actions/setup-java@v4
         with:
-          distribution: adopt
-          java-version: 11
+          distribution: temurin
+          java-version: 21
           cache: gradle
 
       - name: Spotless
diff --git a/build.gradle b/build.gradle
index 4ee5281..f717275 100644
--- a/build.gradle
+++ b/build.gradle
@@ -17,8 +17,8 @@ group "com.autonomouslogic.commons"
 java {
 	withJavadocJar()
 	withSourcesJar()
-	sourceCompatibility = JavaVersion.VERSION_11
-	targetCompatibility = JavaVersion.VERSION_11
+	sourceCompatibility = JavaVersion.VERSION_21
+	targetCompatibility = JavaVersion.VERSION_21
 }
 
 repositories {
@@ -43,6 +43,11 @@ dependencies {
 test {
 	useJUnitPlatform()
 
+	jvmArgs = [
+		"--add-opens", "java.base/java.lang=ALL-UNNAMED",
+		"--add-opens", "java.base/java.util=ALL-UNNAMED"
+	]
+
 	testLogging {
 		events = [ "FAILED", "PASSED", "SKIPPED" ]
 		showExceptions = true