diff --git a/lib/bcoin/lru.js b/lib/bcoin/lru.js
index 160b995b..80028525 100644
--- a/lib/bcoin/lru.js
+++ b/lib/bcoin/lru.js
@@ -139,9 +139,6 @@ LRU.prototype.reset = function reset() {
 LRU.prototype.set = function set(key, value) {
   var item;
 
-  if (value === undefined)
-    throw new Error('Cannot set value to undefined.');
-
   key = key + '';
 
   item = this.data[key];
@@ -196,7 +193,7 @@ LRU.prototype.get = function get(key) {
  */
 
 LRU.prototype.has = function get(key) {
-  return this.data[key] !== undefined;
+  return this.data[key] != null;
 };
 
 /**