diff --git a/lib/bcoin/peer.js b/lib/bcoin/peer.js
index c788d831..d8f57a20 100644
--- a/lib/bcoin/peer.js
+++ b/lib/bcoin/peer.js
@@ -1148,15 +1148,27 @@ Peer.prototype._handleMempool = function _handleMempool() {
   var items = [];
   var i;
 
-  if (!this.mempool)
+  var unlock = this.locker.lock(_handleMempool, []);
+  if (!unlock)
     return;
 
+  function done(err) {
+    if (err) {
+      self.emit('error', err);
+      return unlock();
+    }
+    unlock();
+  }
+
+  if (!this.mempool)
+    return done();
+
   if (this.pool.options.selfish)
-    return;
+    return done();
 
   this.mempool.getSnapshot(function(err, hashes) {
     if (err)
-      return self.emit('error', err);
+      return done(err);
 
     for (i = 0; i < hashes.length; i++)
       items.push({ type: constants.inv.TX, hash: hashes[i] });
@@ -1164,6 +1176,7 @@ Peer.prototype._handleMempool = function _handleMempool() {
     bcoin.debug('Sending mempool snapshot (%s).', self.hostname);
 
     self.sendInv(items);
+    done();
   });
 };