diff --git a/src/main/cpp/algorithms/datastructures/linkedlist/DoublyLinkedList.h b/src/main/cpp/algorithms/datastructures/linkedlist/DoublyLinkedList.h
index 66414c5..b2fc545 100644
--- a/src/main/cpp/algorithms/datastructures/linkedlist/DoublyLinkedList.h
+++ b/src/main/cpp/algorithms/datastructures/linkedlist/DoublyLinkedList.h
@@ -194,7 +194,7 @@ class DoublyLinkedList
 
   // Add an element at a specified index
   void addAt(int index, const T &data) {
-    if (index < 0) {
+    if (index < 0 || index > size_) {
       throw ("Illegal Index");
     }
     if (index == 0) {
diff --git a/src/main/python/algorithms/datastructures/linkedlist/DoublyLinkedList.py b/src/main/python/algorithms/datastructures/linkedlist/DoublyLinkedList.py
index 4435927..78a5748 100644
--- a/src/main/python/algorithms/datastructures/linkedlist/DoublyLinkedList.py
+++ b/src/main/python/algorithms/datastructures/linkedlist/DoublyLinkedList.py
@@ -110,8 +110,8 @@ def addAt(self, index, data):
     """ 
     Add an element at a specified index
     """ 
-    if index < 0:
-      raise Exception('index should not be negative. The value of index was: {}'.format(index))
+    if index < 0 or index > self.llSize:
+      raise Exception('Illegal index. The value of index was: {}'.format(index))
     
     if index == 0:
       self.addFirst(data)