diff --git a/ci-tools/count-vulnerabilities b/ci-tools/count-vulnerabilities
index 9db1c5e7e3aa756dc5b151fbcc30bc4572dd1eba..b1d2b804d81c9c53c0f9a9b41e4e554978c0032d 100755
--- a/ci-tools/count-vulnerabilities
+++ b/ci-tools/count-vulnerabilities
@@ -1,4 +1,5 @@
-#!/usr/bin/env python3
+#! /usr/bin/env nix-shell
+#! nix-shell -i python3 -p python3
 
 from sys import stdin
 from json import load