diff --git a/loleaflet/src/core/Socket.js b/loleaflet/src/core/Socket.js
index 526c51410..310dbbd22 100644
--- a/loleaflet/src/core/Socket.js
+++ b/loleaflet/src/core/Socket.js
@@ -500,7 +500,8 @@ L.Socket = L.Class.extend({
 						console.debug('idleness: reactivating');
 						map._documentIdle = false;
 						// force reinitialization of calcInputBar(formulabar)
-						map.dialog._calcInputBar.id = null;
+						if (map.dialog._calcInputBar)
+							map.dialog._calcInputBar.id = null;
 						return map._activate();
 					}
 					return false;