diff --git a/test/utils.toTwosComplement.js b/test/utils.toTwosComplement.js
new file mode 100644
index 00000000000..b1285de8d8a
--- /dev/null
+++ b/test/utils.toTwosComplement.js
@@ -0,0 +1,41 @@
+/**
+ * Created by danielbruce on 2017-09-25.
+ */
+
+/**
+ * Created by danielbruce on 2017-09-25.
+ */
+var chai = require('chai');
+var utils = require('../lib/utils/utils');
+var BigNumber = require('bignumber.js');
+var assert = chai.assert;
+
+var tests = [
+    { value: 1, expected: new BigNumber(1).round() },
+    { value: '1', expected: new BigNumber(1) },
+    { value: '0x1', expected: new BigNumber(1) },
+    { value: '15', expected: new BigNumber(15)},
+    { value: '0xf', expected: new BigNumber(15)},
+    { value: -1, expected: new BigNumber("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 16).plus(new BigNumber(-1)).plus(1)},
+    { value: '-1', expected: new BigNumber("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 16).plus(new BigNumber(-1)).plus(1)},
+    { value: '-0x1', expected: new BigNumber("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 16).plus(new BigNumber(-1)).plus(1)},
+    { value: '-15', expected: new BigNumber("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 16).plus(new BigNumber(-15)).plus(1)},
+    { value: '-0xf', expected: new BigNumber("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 16).plus(new BigNumber(-15)).plus(1)},
+    { value: 0, expected: new BigNumber(0)},
+    { value: '0', expected: new BigNumber(0)},
+    { value: '0x0', expected: new BigNumber(0)},
+    { value: -0, expected: new BigNumber(0)},
+    { value: '-0', expected: new BigNumber(0)},
+    { value: '-0x0', expected: new BigNumber(0)},
+    { value: new BigNumber(15), expected: new BigNumber(15)}
+];
+
+describe('lib/utils/utils', function () {
+    describe('toTwosComplement', function () {
+        tests.forEach(function (test) {
+            it('printing ' + test.value, function () {
+                assert(test.expected.equals(utils.toTwosComplement(test.value)));
+            });
+        });
+    });
+});