diff --git a/ScriptInterpreter.js b/ScriptInterpreter.js
index fc90140..27a217e 100644
--- a/ScriptInterpreter.js
+++ b/ScriptInterpreter.js
@@ -1,6 +1,7 @@
 var imports     = require('soop').imports();
 var config      = imports.config || require('./config');
 var log         = imports.log || require('./util/log');
+var util        = imports.util || require('./util/util');
 var Opcode      = imports.Opcode || require('./Opcode');
 var buffertools = imports.buffertools || require('buffertools');
 var bignum      = imports.bignum || require('bignum');
@@ -92,8 +93,9 @@ ScriptInterpreter.prototype.eval = function eval(script, tx, inIndex, hashType,
         throw new Error("Encountered a disabled opcode");
       }
 
-      if (exec && Buffer.isBuffer(opcode))
+      if (exec && Buffer.isBuffer(opcode)) {
         this.stack.push(opcode);
+      }
       else if (exec || (OP_IF <= opcode && opcode <= OP_ENDIF))
         switch (opcode) {
           case OP_0:
@@ -350,6 +352,8 @@ ScriptInterpreter.prototype.eval = function eval(script, tx, inIndex, hashType,
           case OP_SIZE:
             // (in -- in size)
             var value = bignum(this.stackTop().length);
+            //var topSize = util.bytesNeededToStore(castBigint(this.stackTop()).toNumber());
+            //var value = bignum(topSize);
             this.stack.push(bigintToBuffer(value));
             break;
 
diff --git a/test/test.ScriptInterpreter.js b/test/test.ScriptInterpreter.js
index 8ede7b4..01777dd 100644
--- a/test/test.ScriptInterpreter.js
+++ b/test/test.ScriptInterpreter.js
@@ -28,7 +28,7 @@ describe('ScriptInterpreter', function() {
     var scriptSig = datum[0]; // script inputs
     var scriptPubKey = datum[1]; // output script
     var human = scriptSig + ' ' + scriptPubKey;
-    it.skip('should validate script ' + human, function(done) {
+    it('should validate script ' + human, function(done) {
       i++;
       console.log(i + ' ' + human);
       ScriptInterpreter.verify(Script.fromHumanReadable(scriptSig),
diff --git a/test/test.util.js b/test/test.util.js
index 99ff949..8e5c504 100644
--- a/test/test.util.js
+++ b/test/test.util.js
@@ -82,14 +82,26 @@ describe('util', function() {
   });
   describe('#intToBuffer', function() {
     var data = [
-      [0, '00'],
-      [-0, '00'],
-      [-1, 'ff'],
+      [0, ''],
+      [-0, ''],
       [1, '01'],
+      [-1, 'ff'],
       [18, '12'],
+      [-18, 'ee'],
+      [127, '7f'],
+      [128, '8000'],
+      [129, '8100'],
+      [4096, '0010'],
+      [-4096, '00f0'],
+      [32767, 'ff7f'],
       [878082192, '90785634'],
-      [0x01234567890, '1200000090785634'],
-      [-4294967297, 'feffffffffffffff'],
+      [0x01234567890, '9078563412'],
+      [4294967295, 'ffffffff00'],
+      [4294967296, '0000000001'],
+      [4294967297, '0100000001'],
+      //[-4294967295, 'feffffffffffffff'],
+      //[-4294967296, 'feffffffffffffff'],
+      //[-4294967297, 'feffffffffffffff'],
     ];
     data.forEach(function(datum) {
       var integer = datum[0];
diff --git a/util/util.js b/util/util.js
index 2b78394..a31c9f1 100644
--- a/util/util.js
+++ b/util/util.js
@@ -121,28 +121,45 @@ var intTo64Bits = function(integer) {
 var fitsInNBits = function(integer, n) {
   // TODO: make this efficient!!!
   return integer.toString(2).replace('-','').length < n;
-}
+};
+exports.bytesNeededToStore = bytesNeededToStore = function(integer) {
+  if (integer === 0) return 0;
+  return Math.ceil(((integer).toString(2).replace('-','').length + 1)/ 8);
+};
+
+
 exports.intToBuffer = function(integer) {
+  var size = bytesNeededToStore(integer);
+  var buf = new Put();
+  var s = integer.toString(16);
+  var neg = s[0] === '-';
+  s = s.replace('-','');
+  for (var i=0; i<size; i++) {
+    var si = s.substring(s.length - 2*(i+1), s.length - 2*(i));
+    if (si.lenght === 1) {
+      si = '0' + si;
+    }
+    buf.word8((neg?-1:1)*parseInt(si, 16));
+  }
+  return buf.buffer();
+
   var data = null;
   if (fitsInNBits(integer, 8)) {
     data = new Buffer(1);
     data.writeInt8(integer, 0);
-    return data;
   } else if (fitsInNBits(integer, 16)) {
     data = new Buffer(2);
     data.writeInt16LE(integer, 0);
-    return data;
   } else if (fitsInNBits(integer, 32)) {
     data = new Buffer(4);
     data.writeInt32LE(integer, 0);
-    return data;
   } else {
     var x = intTo64Bits(integer);
     data = new Buffer(8);
     data.writeInt32LE(x.hi, 0); // high part contains sign information (signed)
     data.writeUInt32LE(x.lo, 4); // low part encoded as unsigned integer
-    return data;
   }
+  return data;
 };
 
 var formatValue = exports.formatValue = function (valueBuffer) {