diff --git a/lib/bcoin/bip151.js b/lib/bcoin/bip151.js
index 662813dc..f462b084 100644
--- a/lib/bcoin/bip151.js
+++ b/lib/bcoin/bip151.js
@@ -70,7 +70,8 @@ function BIP151Stream(cipher, key) {
   this.chacha = new chachapoly.ChaCha20();
   this.aead = new chachapoly.AEAD();
   this.tag = null;
-  this.seq = 0;
+  this.seqHi = 0;
+  this.seqLo = 0;
 
   this.highWaterMark = 1024 * (1 << 20);
   this.processed = 0;
@@ -106,7 +107,8 @@ BIP151Stream.prototype.init = function init(publicKey) {
   this.k2 = utils.hkdfExpand(this.prk, INFO_KEY2, 32, 'sha256');
   this.sid = utils.hkdfExpand(this.prk, INFO_SID, 32, 'sha256');
 
-  this.seq = 0;
+  this.seqHi = 0;
+  this.seqLo = 0;
 
   this.chacha.init(this.k1, this.iv());
   this.aead.init(this.k2, this.iv());
@@ -153,17 +155,18 @@ BIP151Stream.prototype.rekey = function rekey() {
 
 /**
  * Increment packet sequence number and update IVs
- * (note, sequence number overflows after 2^32-1).
+ * (note, sequence number overflows after 2^64-1).
  * The IV will be updated without reinitializing
  * cipher state.
  */
 
 BIP151Stream.prototype.sequence = function sequence() {
-  this.seq++;
-
   // Wrap sequence number a la openssh.
-  if (this.seq === 0x100000000)
-    this.seq = 0;
+  if (++this.seqLo === 0x100000000) {
+    this.seqLo = 0;
+    if (++this.seqHi === 0x100000000)
+      this.seqHi = 0;
+  }
 
   // State of the ciphers is
   // unaltered aside from the iv.
@@ -178,7 +181,8 @@ BIP151Stream.prototype.sequence = function sequence() {
 
 BIP151Stream.prototype.iv = function iv() {
   var p = bcoin.writer();
-  p.writeU64(this.seq);
+  p.writeU32(this.seqLo);
+  p.writeU32(this.seqHi);
   p.writeU32(0);
   return p.render();
 };