diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index 1118f31..97a3007 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -22,10 +22,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: '17'
+          java-version: '21'
           distribution: 'temurin'
 
       - name: Set up Gradle
diff --git a/.github/workflows/loxone-client-release.yml b/.github/workflows/loxone-client-release.yml
index 101a6ad..cd332e1 100644
--- a/.github/workflows/loxone-client-release.yml
+++ b/.github/workflows/loxone-client-release.yml
@@ -25,10 +25,10 @@ jobs:
           ref: master
           token: ${{ secrets.SMARTEON_GIT_TOKEN }}
 
-      - name: Setup JDK 17
+      - name: Setup JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: '17'
+          java-version: '21'
           distribution: 'temurin'
           overwrite-settings: false
 
diff --git a/build.gradle.kts b/build.gradle.kts
index 1835539..87dfc5f 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -39,14 +39,8 @@ detekt {
 }
 
 kotlin {
-    jvmToolchain(17)
+    jvmToolchain(21)
     jvm {
-        compilations.all {
-            kotlinOptions.jvmTarget = JavaVersion.VERSION_11.toString()
-            java {
-                targetCompatibility = JavaVersion.VERSION_11
-            }
-        }
         withJava()
 
         configurations.all {