diff --git a/README.md b/README.md
index 1fb5198..5d485c3 100644
--- a/README.md
+++ b/README.md
@@ -21,3 +21,4 @@ The goal of this project is to get all 500 currently available stars in the form
   - [Day 1](src/Years/Y2015/Day1.md)
   - [Day 2](src/Years/Y2015/Day2.md)
   - [Day 3](src/Years/Y2015/Day3.md)
+  - [Day 4](src/Years/Y2015/Day4.md)