diff --git a/server/build.gradle.kts b/server/build.gradle.kts
index 7dee1e7..4ed6375 100644
--- a/server/build.gradle.kts
+++ b/server/build.gradle.kts
@@ -27,6 +27,10 @@ tasks.withType<ProcessResources> {
     duplicatesStrategy = DuplicatesStrategy.WARN
 }
 
+kotlin {
+    jvmToolchain(21)
+}
+
 dependencies {
     implementation("ai.koog:koog-ktor:$koog_version")
     implementation("io.ktor:ktor-server-csrf")
diff --git a/web/build.gradle.kts b/web/build.gradle.kts
index c58b64f..1ee3c11 100644
--- a/web/build.gradle.kts
+++ b/web/build.gradle.kts
@@ -10,6 +10,7 @@ plugins {
 }
 
 kotlin {
+    jvmToolchain(21)
     @OptIn(org.jetbrains.kotlin.gradle.ExperimentalWasmDsl::class)
     wasmJs {
         browser {