diff --git a/build.gradle.kts b/build.gradle.kts
index 7f700a2f6..31b5447e1 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -3,3 +3,9 @@ plugins {
     eclipse
     id("geyser.base-conventions")
 }
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(21)
+    }
+}