diff --git a/bindings/sdk/src/ffi.udl b/bindings/sdk/src/ffi.udl
index 88cd8613..d981a925 100644
--- a/bindings/sdk/src/ffi.udl
+++ b/bindings/sdk/src/ffi.udl
@@ -43,8 +43,6 @@ typedef string ZkLinkAddress;
 typedef string TxHash;
 [Custom]
 typedef string TxLayer1Signature;
-[Custom]
-typedef string ZkLinkSignature;
 
 // ============================ tx builder  ============================
 dictionary ChangePubKeyBuilder {
@@ -312,6 +310,12 @@ typedef string PackedSignature;
 [Custom]
 typedef string PubKeyHash;
 
+dictionary ZkLinkSignature {
+    PackedPublicKey pub_key;
+    PackedSignature signature;
+};
+
+
 interface ZkLinkSigner {
     [Throws=ZkSignerError]
     constructor();