diff --git a/public/js/icinga/behavior/collapsible.js b/public/js/icinga/behavior/collapsible.js
index 245f021e4..0a4302d2a 100644
--- a/public/js/icinga/behavior/collapsible.js
+++ b/public/js/icinga/behavior/collapsible.js
@@ -132,7 +132,7 @@
                 _this.state.delete(collapsiblePath);
                 _this.collapse($collapsible);
             } else {
-                _this.state.set(collapsiblePath, 1);
+                _this.state.set(collapsiblePath);
                 _this.expand($collapsible);
             }
         }
diff --git a/public/js/icinga/storage.js b/public/js/icinga/storage.js
index af6b3bb1f..03e3f3a2a 100644
--- a/public/js/icinga/storage.js
+++ b/public/js/icinga/storage.js
@@ -312,11 +312,15 @@
          * Set the value for the key in the map
          *
          * @param   {string}    key
-         * @param   {*}         value
+         * @param   {*}         value   Default null
          *
          * @returns {this}
          */
         set: function(key, value) {
+            if (typeof value === 'undefined') {
+                value = null;
+            }
+
             this.data.set(key, {'value': value, 'lastAccess': Date.now()});
 
             this.updateStorage();