diff --git a/lib/mempool/mempool.js b/lib/mempool/mempool.js
index 17567770..2e52c124 100644
--- a/lib/mempool/mempool.js
+++ b/lib/mempool/mempool.js
@@ -83,7 +83,7 @@ function Mempool(options) {
   this.totalTX = 0;
   this.freeCount = 0;
   this.lastTime = 0;
-  this.lastUpdate = 0;
+  this.lastFlush = 0;
 
   this.waiting = {};
   this.orphans = {};
@@ -678,9 +678,9 @@ Mempool.prototype._addTX = co(function* _addTX(tx) {
     throw err;
   }
 
-  if (util.now() - this.lastUpdate > 10) {
+  if (util.now() - this.lastFlush > 10) {
     yield this.cache.flush();
-    this.lastUpdate = util.now();
+    this.lastFlush = util.now();
   }
 
   return missing;