diff --git a/bip-0374/reference.py b/bip-0374/reference.py
old mode 100644
new mode 100755
index e375bd72..bfb7f0bb
--- a/bip-0374/reference.py
+++ b/bip-0374/reference.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 """Reference implementation of DLEQ BIP for secp256k1 with unit tests."""
 
 from hashlib import sha256