diff --git a/src/test/kotlin/kr/galaxyhub/sc/config/TestContainerExtension.kt b/src/test/kotlin/kr/galaxyhub/sc/config/TestContainerExtension.kt
index 7aa545c..8676f5d 100644
--- a/src/test/kotlin/kr/galaxyhub/sc/config/TestContainerExtension.kt
+++ b/src/test/kotlin/kr/galaxyhub/sc/config/TestContainerExtension.kt
@@ -14,7 +14,7 @@ import org.testcontainers.containers.wait.strategy.ShellStrategy
 @AutoScan
 class TestContainerExtension : ProjectExtension {
 
-    private var containers = mutableListOf<DockerComposeContainer<*>>()
+    private val containers = mutableListOf<DockerComposeContainer<*>>()
 
     override suspend fun interceptProject(context: ProjectContext, callback: suspend (ProjectContext) -> Unit) {
         if (isTestcontianersEnable(context)) {