diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index 88403141..f6f472ef 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -574,6 +574,8 @@ Mempool.prototype.countAncestors = function countAncestors(tx, callback) {
       if (!tx)
         return next();
 
+      inputs[i] += 1;
+
       self.countAncestors(tx, function(err, max) {
         if (err)
           return next(err);