diff --git a/capture_the_flag/README.md b/capture_the_flag/README.md
index 9c3142e..644aac5 100644
--- a/capture_the_flag/README.md
+++ b/capture_the_flag/README.md
@@ -5,3 +5,4 @@ Capture the flag (CTF) is a computer security competition that is designed for e
 * https://ctf365.com
 * http://captf.com
 * https://pentesterlab.com/exercises
+* http://vulnhub.com