diff --git a/src/main/java/com/alibaba/ttl/TransmittableThreadLocal.java b/src/main/java/com/alibaba/ttl/TransmittableThreadLocal.java
index d062504af..13e523897 100644
--- a/src/main/java/com/alibaba/ttl/TransmittableThreadLocal.java
+++ b/src/main/java/com/alibaba/ttl/TransmittableThreadLocal.java
@@ -227,7 +227,8 @@ private void removeThisFromHolder() {
     }
 
     private static void doExecuteCallback(boolean isBefore) {
-        for (TransmittableThreadLocal<Object> threadLocal : holder.get().keySet()) {
+        WeakHashMap<TransmittableThreadLocal<Object>, ?> ttlInstances = new WeakHashMap<TransmittableThreadLocal<Object>, Object>(holder.get());
+        for (TransmittableThreadLocal<Object> threadLocal : ttlInstances.keySet()) {
             try {
                 if (isBefore) threadLocal.beforeExecute();
                 else threadLocal.afterExecute();