diff --git a/core/src/main/java/com/taobao/arthas/core/server/instrument/ClassLoader_Instrument.java b/core/src/main/java/com/taobao/arthas/core/server/instrument/ClassLoader_Instrument.java
index 702ec5c51..117ad4891 100644
--- a/core/src/main/java/com/taobao/arthas/core/server/instrument/ClassLoader_Instrument.java
+++ b/core/src/main/java/com/taobao/arthas/core/server/instrument/ClassLoader_Instrument.java
@@ -12,7 +12,10 @@ import com.alibaba.bytekit.agent.inst.InstrumentApi;
 public abstract class ClassLoader_Instrument {
     public Class<?> loadClass(String name) throws ClassNotFoundException {
         if (name.startsWith("java.arthas.")) {
-            return ClassLoader.getSystemClassLoader().loadClass(name);
+            ClassLoader extClassLoader = ClassLoader.getSystemClassLoader().getParent();
+            if (extClassLoader != null) {
+                return extClassLoader.loadClass(name);
+            }
         }
 
         Class clazz = InstrumentApi.invokeOrigin();