diff --git a/oop/notes/01-oop-introduction.md b/oop/notes/01-oop-introduction.md
index 8202c49..32672cb 100644
--- a/oop/notes/01-oop-introduction.md
+++ b/oop/notes/01-oop-introduction.md
@@ -146,7 +146,7 @@ def transfer(source: int, destination: int, amount: int) -> None:
 def get_account(number: int) -> dict:
     return list(filter(lambda account: account['number'] == number, accounts))[0]
 
-def update_account(account: int, delta: int) -> None:
+def update_account(account: dict, delta: int) -> None:
     account['balance'] += delta
 ```
 
@@ -264,4 +264,4 @@ System.out.println(instance2.name); // Asia Cup 2023
 * [Banana-gorilla problem](https://dev.to/efpage/what-s-wrong-with-the-gorilla-2l4j#:~:text=Joe%20Armstrong%2C%20the%20principal%20inventor,and%20the%20entire%20jungle.%22.)
 * [Abstraction](https://levelup.gitconnected.com/abstraction-in-object-oriented-programming-a28a0e534f75)
 * [Abstraction in Python](https://www.askpython.com/python/oops/abstraction-in-python)
-* [Abstraction in Javascript](https://viktor-kukurba.medium.com/object-oriented-programming-in-javascript-1-abstraction-c47307c469d1)
\ No newline at end of file
+* [Abstraction in Javascript](https://viktor-kukurba.medium.com/object-oriented-programming-in-javascript-1-abstraction-c47307c469d1)