diff --git a/lib/http/rpcbase.js b/lib/http/rpcbase.js
index 7891fe84..fb31f6e4 100644
--- a/lib/http/rpcbase.js
+++ b/lib/http/rpcbase.js
@@ -70,10 +70,7 @@ RPCBase.prototype.call = co(function* call(body, query) {
 
     assert(Array.isArray(cmd.params), 'Params must be an array.');
 
-    if (!cmd.id)
-      cmd.id = 0;
-
-    assert(typeof cmd.id === 'number', 'ID must be a number.');
+    enforce(!cmd.id || typeof cmd.id !== 'object', 'Invalid ID.');
   }
 
   for (i = 0; i < cmds.length; i++) {