diff --git a/lib/client/api.js b/lib/client/api.js
index c1750f9..e9f7ac7 100644
--- a/lib/client/api.js
+++ b/lib/client/api.js
@@ -18,8 +18,8 @@ var BASE_URL = 'http://localhost:3001/copay/api';
 var WALLET_CRITICAL_DATA = ['xPrivKey', 'm', 'publicKeyRing'];
 
 function _createProposalOpts(opts, signingKey) {
-  var msg = opts.toAddress + '|' + opts.amount + '|' + opts.message;
-  opts.proposalSignature = WalletUtils.signMessage(msg, signingKey);
+  var hash = WalletUtils.getProposalHash(opts.toAddress, opts.amount, opts.message);
+  opts.proposalSignature = WalletUtils.signMessage(hash, signingKey);
   return opts;
 };