diff --git a/common/modules/addons.jsm b/common/modules/addons.jsm
index 487f2f90..017f20f7 100644
--- a/common/modules/addons.jsm
+++ b/common/modules/addons.jsm
@@ -388,7 +388,7 @@ var Addons = Module("addons", {
             "Install an extension",
             function (args) {
                 let url  = args[0];
-                let file = io.File(url);
+                let file = modules.io.File(url);
                 function install(addonInstall) {
                     addonInstall.addListener(addonListener);
                     addonInstall.install();