diff --git a/core/src/main/java/com/taobao/arthas/core/shell/term/impl/CompletionAdaptor.java b/core/src/main/java/com/taobao/arthas/core/shell/term/impl/CompletionAdaptor.java
index 2d03ea877..2008b1c0e 100644
--- a/core/src/main/java/com/taobao/arthas/core/shell/term/impl/CompletionAdaptor.java
+++ b/core/src/main/java/com/taobao/arthas/core/shell/term/impl/CompletionAdaptor.java
@@ -43,7 +43,7 @@ class CompletionAdaptor implements Completion {
 
     @Override
     public void complete(List<String> candidates) {
-        String lastToken = tokens.get(tokens.size() - 1).value();
+        String lastToken = tokens.isEmpty() ? null : tokens.get(tokens.size() - 1).value();
         if(StringUtils.isBlank(lastToken)) {
             lastToken = "";
         }