diff --git a/2021/IK-31/Rybak/README.md b/2021/IK-31/Rybak/README.md
index e8555f3c..17c2c82f 100644
--- a/2021/IK-31/Rybak/README.md
+++ b/2021/IK-31/Rybak/README.md
@@ -5,5 +5,6 @@
 | Lab #2a |[Посилання](https://github.com/Yura47/Yurii-Rybak-IK-31/tree/master/Lab_2a) |
 | Lab #2 |[Посилання](https://github.com/Yura47/Yurii-Rybak-IK-31/tree/master/lab_2) |
 | Lab #3 |[Посилання](https://github.com/Yura47/Yurii-Rybak-IK-31/tree/master/lab_3) |
+| Lab #4 |[Посилання](https://github.com/Yura47/Yurii-Rybak-IK-31/tree/master/lab_4) |