diff --git a/src/main/java/com/sparrowwallet/drongo/wallet/WalletNode.java b/src/main/java/com/sparrowwallet/drongo/wallet/WalletNode.java
index 269e99e..5e2b502 100644
--- a/src/main/java/com/sparrowwallet/drongo/wallet/WalletNode.java
+++ b/src/main/java/com/sparrowwallet/drongo/wallet/WalletNode.java
@@ -325,7 +325,7 @@ public class WalletNode extends Persistable implements Comparable<WalletNode> {
         copy.setId(getId());
         copy.setLabel(label);
 
-        for(WalletNode child : getChildren()) {
+        for(WalletNode child : new ArrayList<>(getChildren())) {
             copy.children.add(child.copy(walletCopy));
         }