diff --git a/build.gradle b/build.gradle
index b12d9d5..72d92eb 100644
--- a/build.gradle
+++ b/build.gradle
@@ -9,7 +9,7 @@ wrapper {
 }
 
 java.toolchain {
-    languageVersion = JavaLanguageVersion.of(21)
+    languageVersion = JavaLanguageVersion.of(17)
 }
 
 group = "ru.di9"