diff --git a/core/src/main/java/io/servicecomb/core/definition/classloader/PrivateMicroserviceClassLoaderFactory.java b/core/src/main/java/io/servicecomb/core/definition/classloader/PrivateMicroserviceClassLoaderFactory.java
index 435bdc773ce..110e47811bf 100644
--- a/core/src/main/java/io/servicecomb/core/definition/classloader/PrivateMicroserviceClassLoaderFactory.java
+++ b/core/src/main/java/io/servicecomb/core/definition/classloader/PrivateMicroserviceClassLoaderFactory.java
@@ -17,8 +17,11 @@
 package io.servicecomb.core.definition.classloader;
 
 public class PrivateMicroserviceClassLoaderFactory implements MicroserviceClassLoaderFactory {
+
   public static final MicroserviceClassLoaderFactory INSTANCE = new PrivateMicroserviceClassLoaderFactory();
 
+  private PrivateMicroserviceClassLoaderFactory() {}
+
   @Override
   public ClassLoader create(String appId, String microserviceName, String version) {
     return new MicroserviceClassLoader(appId, microserviceName, version);
diff --git a/core/src/main/java/io/servicecomb/core/definition/loader/DynamicSchemaLoader.java b/core/src/main/java/io/servicecomb/core/definition/loader/DynamicSchemaLoader.java
index caceb770a42..7214e48fc63 100644
--- a/core/src/main/java/io/servicecomb/core/definition/loader/DynamicSchemaLoader.java
+++ b/core/src/main/java/io/servicecomb/core/definition/loader/DynamicSchemaLoader.java
@@ -44,6 +44,8 @@ public class DynamicSchemaLoader {
 
   public static final DynamicSchemaLoader INSTANCE = new DynamicSchemaLoader();
 
+  private DynamicSchemaLoader() {}
+
   /**
    * 动态注册指定目录下的schema契约到当前服务
    * @param schemaLocation eg. "classpath*:schemas/*.yaml"