diff --git a/lib/crypto/signature.js b/lib/crypto/signature.js
index a179afe5c..cf9b897c2 100644
--- a/lib/crypto/signature.js
+++ b/lib/crypto/signature.js
@@ -4,6 +4,7 @@ var BN = require('./bn');
 var _ = require('lodash');
 var $ = require('../util/preconditions');
 var BufferUtil = require('../util/buffer');
+var JSUtil = require('../util/js');
 
 var Signature = function Signature(r, s) {
   if (!(this instanceof Signature)) {
@@ -285,7 +286,12 @@ Signature.prototype.hasLowS = function() {
  * Translated from bitcoind's IsDefinedHashtypeSignature
  */
 Signature.prototype.hasDefinedHashtype = function() {
-  if (this.nhashtype < Signature.SIGHASH_ALL || this.nhashtype > Signature.SIGHASH_SINGLE) {
+  if (!JSUtil.isNaturalNumber(this.nhashtype)) {
+    return false;
+  }
+  // accept with or without Signature.SIGHASH_ANYONECANPAY by ignoring the bit
+  var temp = this.nhashtype & ~Signature.SIGHASH_ANYONECANPAY;
+  if (temp < Signature.SIGHASH_ALL || temp > Signature.SIGHASH_SINGLE) {
     return false;
   }
   return true;
diff --git a/test/crypto/signature.js b/test/crypto/signature.js
index 359c96d2d..dc005491b 100644
--- a/test/crypto/signature.js
+++ b/test/crypto/signature.js
@@ -1,5 +1,6 @@
 'use strict';
 
+var _ = require('lodash');
 var should = require('chai').should();
 var bitcore = require('../..');
 var BN = bitcore.crypto.BN;
@@ -293,4 +294,35 @@ describe('Signature', function() {
     });
   });
 
+  describe('#hasDefinedHashtype', function() {
+    it('should reject invalid sighash types and accept valid ones', function() {
+      var sig = new Signature();
+      sig.hasDefinedHashtype().should.equal(false);
+      var testCases = [
+        [undefined, false],
+        [null, false],
+        [0, false],
+        [1.1, false],
+        [-1, false],
+        [-1.1, false],
+        ['', false],
+        ['1', false],
+        [Signature.SIGHASH_ANYONECANPAY, false],
+        [Signature.SIGHASH_ANYONECANPAY | Signature.SIGHASH_ALL, true],
+        [Signature.SIGHASH_ANYONECANPAY | Signature.SIGHASH_NONE, true],
+        [Signature.SIGHASH_ANYONECANPAY | Signature.SIGHASH_SINGLE, true],
+        [Signature.SIGHASH_ALL, true],
+        [Signature.SIGHASH_NONE, true],
+        [Signature.SIGHASH_SINGLE, true],
+        [Signature.SIGHASH_SINGLE + 1, false],
+        [(Signature.SIGHASH_ANYONECANPAY | Signature.SIGHASH_SINGLE) + 1, false],
+        [(Signature.SIGHASH_ANYONECANPAY | Signature.SIGHASH_ALL) - 1, false],
+      ];
+      _.each(testCases, function(testCase) {
+        sig.nhashtype = testCase[0];
+        sig.hasDefinedHashtype().should.equal(testCase[1]);
+      });
+    });
+  });
+
 });