diff --git a/lib/protocol/consensus.js b/lib/protocol/consensus.js
index d144108a..36f8e072 100644
--- a/lib/protocol/consensus.js
+++ b/lib/protocol/consensus.js
@@ -323,6 +323,9 @@ exports.verifyPOW = function verifyPOW(hash, bits) {
   if (target.isNeg() || target.isZero())
     return false;
 
+  if (target.bitLength() > 256)
+    return false;
+
   const num = new BN(hash, 'le');
 
   if (num.gt(target))