diff --git a/lib/mining/minerblock.js b/lib/mining/minerblock.js
index b3db5ef9..494fb542 100644
--- a/lib/mining/minerblock.js
+++ b/lib/mining/minerblock.js
@@ -230,12 +230,13 @@ MinerBlock.prototype.updateNonce = function updateNonce() {
 
   // Overflow the nonce and increment the extraNonce.
   this.block.nonce = 0;
-
   this.nonce1++;
-  this.nonce1 &= 0xffffffffffff;
 
-  if (this.nonce1 === 0)
+  // Wrap at 6 bytes.
+  if (this.nonce1 === 0xffffffffffff) {
+    this.nonce1 = 0;
     this.nonce2++;
+  }
 
   // We incremented the extraNonce, need to update coinbase.
   this.updateCoinbase();