--- a/addon-sdk/source/lib/sdk/addon/installer.js
+++ b/addon-sdk/source/lib/sdk/addon/installer.js
@@ -59,17 +59,17 @@ exports.install = function install(xpiPa
     },
     onDownloadFailed: function(aInstall) {
       this.onInstallFailed(aInstall);
     }
   };
 
   // Order AddonManager to install the addon
   AddonManager.getInstallForFile(file, function(install) {
-    if (install.error != null) {
+    if (install.error == 0) {
       install.addListener(listener);
       install.install();
     } else {
       reject(install.error);
     }
   });
 
   return promise;