diff --git a/lib/script_interpreter.js b/lib/script_interpreter.js
index 88b1f0d..cbcc7e0 100644
--- a/lib/script_interpreter.js
+++ b/lib/script_interpreter.js
@@ -162,6 +162,7 @@ ScriptInterpreter.prototype.checkPubkeyEncoding = function(buf) {
  * bitcoind commit: b5d1b1092998bc95313856d535c632ea5a8f9104
  */
 ScriptInterpreter.prototype.evaluate = function() {
+  console.log(this.script.toString());
   if (this.script.toBuffer().length > 10000) {
     this.errstr = 'SCRIPT_ERR_SCRIPT_SIZE';
     return false;
@@ -883,7 +884,6 @@ ScriptInterpreter.prototype.step = function() {
           subscript.findAndDelete(tmpScript);
 
           if (!this.checkSignatureEncoding(bufSig) || !this.checkPubkeyEncoding(bufPubkey)) {
-            // serror is set
             return false;
           }
 
@@ -973,7 +973,6 @@ ScriptInterpreter.prototype.step = function() {
             var bufPubkey = this.stack[this.stack.length - ikey];
 
             if (!this.checkSignatureEncoding(bufSig) || !this.checkPubkeyEncoding(bufPubkey)) {
-              // serror is set
               return false;
             }
 
@@ -1141,7 +1140,6 @@ ScriptInterpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin,
 
     // evaluate redeemScript
     if (!this.evaluate())
-    // serror is set
       return false;
 
     if (stackCopy.length === 0) {
diff --git a/lib/transaction/sighash.js b/lib/transaction/sighash.js
index 0d2782f..30ebf6f 100644
--- a/lib/transaction/sighash.js
+++ b/lib/transaction/sighash.js
@@ -11,6 +11,7 @@ var BN = require('../crypto/bn');
 var Hash = require('../crypto/hash');
 var ECDSA = require('../crypto/ecdsa');
 var $ = require('../util/preconditions');
+var _ = require('lodash');
 
 var SIGHASH_SINGLE_BUG = '0000000000000000000000000000000000000000000000000000000000000001';
 var BITS_64_ON = 'ffffffffffffffff';
@@ -122,8 +123,8 @@ function sign(transaction, privateKey, sighashType, inputIndex, subscript) {
  * @return {boolean}
  */
 function verify(transaction, signature, publicKey, inputIndex, subscript) {
-  $.checkArgument(transaction);
-  $.checkArgument(signature && signature.nhashtype);
+  $.checkArgument(!_.isUndefined(transaction));
+  $.checkArgument(!_.isUndefined(signature) && !_.isUndefined(signature.nhashtype));
   var hashbuf = sighash(transaction, signature.nhashtype, inputIndex, subscript);
   return ECDSA.verify(hashbuf, signature, publicKey, 'little');
 }
diff --git a/test/script_interpreter.js b/test/script_interpreter.js
index 085602a..aa84687 100644
--- a/test/script_interpreter.js
+++ b/test/script_interpreter.js
@@ -247,7 +247,6 @@ describe('ScriptInterpreter', function() {
 
         var tx = Transaction(txhex);
         tx.inputs.forEach(function(txin, j) {
-          console.log('input ' + j);
           var scriptSig = txin.script;
           var txidhex = txin.prevTxId.toString('hex');
           var txoutnum = txin.outputIndex;