diff --git a/lib/net/hostlist.js b/lib/net/hostlist.js
index e8937503..a70e70aa 100644
--- a/lib/net/hostlist.js
+++ b/lib/net/hostlist.js
@@ -69,6 +69,14 @@ function HostList(options) {
   this._init();
 }
 
+/**
+ * Serialization version.
+ * @const {Number}
+ * @default
+ */
+
+HostList.VERSION = 0;
+
 /**
  * Initialize options.
  * @private
@@ -972,7 +980,7 @@ HostList.prototype.toJSON = function toJSON() {
   }
 
   return {
-    version: 1,
+    version: HostList.VERSION,
     addrs: addrs,
     fresh: fresh,
     used: used
@@ -996,7 +1004,9 @@ HostList.prototype.fromJSON = function fromJSON(json) {
   var i, j, bucket, keys, key, addr, entry, src;
 
   assert(json && typeof json === 'object');
-  assert(json.version === 1, 'Bad address serialization version.');
+
+  assert(json.version === HostList.VERSION,
+    'Bad address serialization version.');
 
   assert(Array.isArray(json.addrs));