diff --git a/package.json b/package.json
index 1e698af..60fbcf8 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@kilnfi/sdk",
-  "version": "4.2.21",
+  "version": "4.2.22",
   "autor": "Kiln <support@kiln.fi> (https://kiln.fi)",
   "license": "BUSL-1.1",
   "description": "JavaScript sdk for Kiln API",
diff --git a/src/fireblocks.ts b/src/fireblocks.ts
index 761845b..902b078 100644
--- a/src/fireblocks.ts
+++ b/src/fireblocks.ts
@@ -1459,6 +1459,10 @@ export class FireblocksService {
         messages: [
           {
             content: tx.unsigned_tx_hash,
+            preHash: {
+              content: tx.unsigned_tx_serialized,
+              hashAlgorithm: 'SHA256',
+            },
           },
         ],
       },