diff --git a/lib/bcoin/bip151.js b/lib/bcoin/bip151.js
index 24dc76d9..220124c9 100644
--- a/lib/bcoin/bip151.js
+++ b/lib/bcoin/bip151.js
@@ -164,14 +164,8 @@ BIP151.prototype.toEncack = function toEncack(writer) {
 BIP151.prototype.encack = function encack(data) {
   var p = bcoin.reader(data);
   var publicKey = p.readBytes(33);
-  var i;
 
-  for (i = 0; i < publicKey.length; i++) {
-    if (publicKey[i] !== 0)
-      break;
-  }
-
-  if (i === publicKey.length) {
+  if (utils.isZero(publicKey)) {
     this.rekey();
     return;
   }
diff --git a/lib/bcoin/utils.js b/lib/bcoin/utils.js
index eafbfcdb..c7b0880e 100644
--- a/lib/bcoin/utils.js
+++ b/lib/bcoin/utils.js
@@ -1741,6 +1741,25 @@ utils.sizeVarint2 = function sizeVarint2(num) {
   return size;
 };
 
+/**
+ * Test whether a buffer is all zeroes.
+ * @param {Buffer} data
+ * @returns {Boolean}
+ */
+
+utils.isZero = function isZero(data) {
+  var i;
+
+  assert(Buffer.isBuffer(data));
+
+  for (i = 0; i < data.length; i++) {
+    if (data[i] !== 0)
+      return false;
+  }
+
+  return true;
+};
+
 /**
  * Buffer comparator (memcmp + length comparison).
  * @param {Buffer} a