1 files changed, 4 insertions, 2 deletions
diff --git a/lib/HostMap.jsm b/lib/HostMap.jsm
index 308c825..59d4f65 100644
--- a/lib/HostMap.jsm
+++ b/lib/HostMap.jsm
@@ -23,13 +23,15 @@
 
 'use strict';
 
+var Ci = Components.interfaces;
+
 var EXPORTED_SYMBOLS = ['HostMap'];
 
 var map = new Map();
 
 var HostMap = {
     put: function (key, value) {
-        if (typeof key !== 'string' || typeof value !== 'string'
+        if (!(key instanceof Ci.nsIURI) || !(value instanceof Ci.nsIURI)
             || !key || !value) {
             throw new Error('invalid argument(s)');
         }
@@ -41,7 +43,7 @@ var HostMap = {
         map.set(key, value);
     },
     get: function (key) {
-        if (typeof key !== 'string' || !key) {
+        if (!(key instanceof Ci.nsIURI) || !key) {
             throw new Error('invalid argument');
         }