diff --git a/Priority Queue/SimplePriorityQueue.cs b/Priority Queue/SimplePriorityQueue.cs
index 7ac36b7..f8e3a32 100644
--- a/Priority Queue/SimplePriorityQueue.cs	
+++ b/Priority Queue/SimplePriorityQueue.cs	
@@ -171,7 +171,11 @@ public bool Contains(TItem item)
         {
             lock(_queue)
             {
-                return GetExistingNode(item) != null;
+                if (item == null)
+                {
+                    return _nullNodesCache.Count > 0;
+                }
+                return _itemToNodesCache.ContainsKey(item);
             }
         }