diff --git a/js/models/core/BuilderMockV0.js b/js/models/core/BuilderMockV0.js
deleted file mode 100644
index be3926d10..000000000
--- a/js/models/core/BuilderMockV0.js
+++ /dev/null
@@ -1,26 +0,0 @@
-'use strict';
-
-
-var bitcore = require('bitcore');
-var Transaction = bitcore.Transaction;
-
-function BuilderMockV0 (data) {
-  this.vanilla = data;
-  this.tx = new Transaction();
-  this.tx.parse(new Buffer(data.tx, 'hex'));
-};
-
-BuilderMockV0.prototype.build = function() {
-  return this.tx;
-}; 
-
-
-BuilderMockV0.prototype.getSelectedUnspent = function() {
-  return [];
-};
-
-BuilderMockV0.prototype.toObj = function() {
-  return this.vanilla;
-};
-
-module.exports = BuilderMockV0;
diff --git a/js/models/core/TxProposal.js b/js/models/core/TxProposal.js
index 2c7b6d02b..88046ca62 100644
--- a/js/models/core/TxProposal.js
+++ b/js/models/core/TxProposal.js
@@ -3,7 +3,6 @@
 var bitcore = require('bitcore');
 var util = bitcore.util;
 var Transaction = bitcore.Transaction;
-var BuilderMockV0 = require('./BuilderMockV0');;
 var TransactionBuilder = bitcore.TransactionBuilder;
 var Script = bitcore.Script;
 var Key = bitcore.Key;
@@ -136,12 +135,7 @@ TxProposal.fromObj = function(o, forceOpts) {
     }
     o.builder = TransactionBuilder.fromObj(o.builderObj);
   } catch (e) {
-
-    // backwards (V0) compatatibility fix.
-    if (!o.version) {
-      o.builder = new BuilderMockV0(o.builderObj);
-      o.readonly = 1;
-    };
+    throw new Error("Old version of wallet detected.");
   }
   return new TxProposal(o);
 };
diff --git a/js/models/core/TxProposals.js b/js/models/core/TxProposals.js
index 11d9ad3b8..6f4cbc625 100644
--- a/js/models/core/TxProposals.js
+++ b/js/models/core/TxProposals.js
@@ -1,11 +1,9 @@
 'use strict';
 
-var BuilderMockV0 = require('./BuilderMockV0');;
 var bitcore = require('bitcore');
 var util = bitcore.util;
 var Transaction = bitcore.Transaction;
-var BuilderMockV0 = require('./BuilderMockV0');;
-var TxProposal = require('./TxProposal');;
+var TxProposal = require('./TxProposal');
 var Script = bitcore.Script;
 var Key = bitcore.Key;
 var buffertools = bitcore.buffertools;