diff --git a/package-lock.json b/package-lock.json
index 8c1da38..b2cd38f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@archethicjs/sdk",
-  "version": "1.21.3",
+  "version": "1.21.4",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "@archethicjs/sdk",
-      "version": "1.21.3",
+      "version": "1.21.4",
       "license": "AGPL-3.0-or-later",
       "dependencies": {
         "@absinthe/socket": "^0.2.1",
diff --git a/package.json b/package.json
index 2a59d24..3a77ba8 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@archethicjs/sdk",
-  "version": "1.21.3",
+  "version": "1.21.4",
   "description": "Archethic Javascript SDK",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
diff --git a/src/transaction_builder.ts b/src/transaction_builder.ts
index 846f9f3..016a769 100644
--- a/src/transaction_builder.ts
+++ b/src/transaction_builder.ts
@@ -162,8 +162,8 @@ export default class TransactionBuilder {
   addUCOTransfer(to: string | Uint8Array, amount: bigint) {
     to = maybeHexToUint8Array(to);
 
-    if (amount <= 0) {
-      throw new Error("UCO transfer amount must be a positive number");
+    if (amount < 0) {
+      throw new Error("UCO transfer amount cannot be negative");
     }
 
     this.data.ledger.uco.transfers.push({ to, amount });