diff --git a/common/modules/sanitizer.jsm b/common/modules/sanitizer.jsm
index 30bebda7..8d966d36 100644
--- a/common/modules/sanitizer.jsm
+++ b/common/modules/sanitizer.jsm
@@ -456,7 +456,9 @@ var Sanitizer = Module("sanitizer", XPCOM([Ci.nsIObserver, Ci.nsISupportsWeakRef
                     opt = { __proto__: opt, value: args.slice() };
                 }
 
-                let items = Object.keys(sanitizer.itemMap).slice(1).filter(opt.has, opt);
+                let items = Object.keys(sanitizer.itemMap)
+                                  .slice(1)
+                                  .filter(opt.has, opt);
 
                 function sanitize(items) {
                     sanitizer.range = range.native;
diff --git a/common/modules/storage.jsm b/common/modules/storage.jsm
index fd8f7924..339cafbe 100644
--- a/common/modules/storage.jsm
+++ b/common/modules/storage.jsm
@@ -308,7 +308,7 @@ var Storage = Module("Storage", {
 
     addObserver: function addObserver(key, callback, window) {
         var { observers } = this;
-        if (window)
+        if (window instanceof Ci.nsIDOMWindow)
             observers = overlay.getData(window, "storage-observers", Object);
 
         if (!hasOwnProperty(observers, key))