diff --git a/KotlinCore/build.gradle.kts b/KotlinCore/build.gradle.kts
index 6c16669c..770a4215 100644
--- a/KotlinCore/build.gradle.kts
+++ b/KotlinCore/build.gradle.kts
@@ -40,8 +40,8 @@ tasks.shadowJar {
 }
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_21
-    targetCompatibility = JavaVersion.VERSION_21
+    sourceCompatibility = JavaVersion.VERSION_17
+    targetCompatibility = JavaVersion.VERSION_17
 }
 
 sourceSets {
@@ -63,5 +63,5 @@ dependencies {
 }
 
 kotlin {
-    jvmToolchain(21)
+    jvmToolchain(17)
 }
\ No newline at end of file