diff --git a/packages/protocol/contracts/L2/DelegateOwner.sol b/packages/protocol/contracts/L2/DelegateOwner.sol
index 06d8d2e9799..235208ea84d 100644
--- a/packages/protocol/contracts/L2/DelegateOwner.sol
+++ b/packages/protocol/contracts/L2/DelegateOwner.sol
@@ -3,6 +3,7 @@ pragma solidity 0.8.24;
 
 import "../common/EssentialContract.sol";
 import "../common/LibStrings.sol";
+import "../libs/LibAddress.sol";
 import "../libs/LibBytes.sol";
 import "../bridge/IBridge.sol";
 
@@ -41,6 +42,7 @@ contract DelegateOwner is EssentialContract, IMessageInvocable {
 
     error DO_DRYRUN_SUCCEEDED();
     error DO_INVALID_PARAM();
+    error DO_INVALID_TARGET();
     error DO_INVALID_TX_ID();
     error DO_PERMISSION_DENIED();
     error DO_TARGET_CALL_REVERTED();
@@ -106,6 +108,9 @@ contract DelegateOwner is EssentialContract, IMessageInvocable {
 
         if (_verifyTxId && call.txId != nextTxId++) revert DO_INVALID_TX_ID();
 
+        // By design, the target must be a contract address.
+        if (!Address.isContract(call.target)) revert DO_INVALID_TARGET();
+
         (bool success, bytes memory result) = call.isDelegateCall //
             ? call.target.delegatecall(call.txdata)
             : call.target.call{ value: msg.value }(call.txdata);