diff --git a/lib/bcoin/miner.js b/lib/bcoin/miner.js
index eccde6b6..c4d7f44f 100644
--- a/lib/bcoin/miner.js
+++ b/lib/bcoin/miner.js
@@ -36,14 +36,19 @@ exports.miner = function miner(options, callback) {
   }
 
   function addTX(tx) {
-    var s;
+    if (tx.inputs[0].output && !tx.verify())
+      return;
+
     if (tx.height !== -1)
       return;
-    s = tx.render().length;
-    if (block.size() + s > constants.blocks.maxSize)
+
+    if (block.size() + tx.size() > constants.blocks.maxSize)
       return;
+
     nextBlock.txs.push(tx);
+
     fee.iadd(tx.getFee());
+
     // Update coinbase value
     updateCoinbase(nextBlock);
     // Update merkle root for new coinbase and new tx