diff --git a/src/org/redkale/service/RetResult.java b/src/org/redkale/service/RetResult.java
index c5d6695bd..c9c381bd7 100644
--- a/src/org/redkale/service/RetResult.java
+++ b/src/org/redkale/service/RetResult.java
@@ -124,7 +124,7 @@ public class RetResult<T> {
      */
     public RetResult<T> attach(String key, Object value) {
         if (this.attach == null) this.attach = new HashMap<>();
-        boolean canstr = value instanceof CharSequence || value.getClass().isPrimitive();
+        boolean canstr = value != null && (value instanceof CharSequence || value.getClass().isPrimitive());
         this.attach.put(key, value == null ? null : (canstr ? String.valueOf(value) : JsonConvert.root().convertTo(value)));
         return this;
     }