diff --git a/StringValue.cpp b/StringValue.cpp
index 26b8acf..90426ad 100644
--- a/StringValue.cpp
+++ b/StringValue.cpp
@@ -25,7 +25,7 @@ void StringValue::operator--()
 
 const char& StringValue::operator[](size_t index) const
 {
-    if (index > _size-1)
+    if (index > _size - 2)
         throw std::out_of_range("Index out of range!");
     return _data[index];
 }