diff --git a/tools/quick-e2e/build.gradle.kts b/tools/quick-e2e/build.gradle.kts
index c48fc6db..4920448d 100644
--- a/tools/quick-e2e/build.gradle.kts
+++ b/tools/quick-e2e/build.gradle.kts
@@ -8,7 +8,7 @@ group = "de.oliver"
 description = "Tool to setup a complete environment for testing"
 
 java {
-    toolchain.languageVersion.set(JavaLanguageVersion.of(23))
+    toolchain.languageVersion.set(JavaLanguageVersion.of(21))
 }
 
 repositories {
@@ -42,7 +42,7 @@ tasks {
 
         // Set the release flag. This configures what version bytecode the compiler will emit, as well as what JDK APIs are usable.
         // See https://openjdk.java.net/jeps/247 for more information.
-        options.release.set(23)
+        options.release.set(21)
     }
 
     java {