diff --git a/libraries/AP_NavEKF3/derivation/code_gen.py b/libraries/AP_NavEKF3/derivation/code_gen.py
index 9e193b65ee..8aa14500b0 100644
--- a/libraries/AP_NavEKF3/derivation/code_gen.py
+++ b/libraries/AP_NavEKF3/derivation/code_gen.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 # Taken from https://github.com/PX4/ecl/commit/264c8c4e8681704e4719d0a03b848df8617c0863
 # and modified for ArduPilot
diff --git a/libraries/AP_NavEKF3/derivation/main.py b/libraries/AP_NavEKF3/derivation/main.py
old mode 100644
new mode 100755
index fdbd4e26a7..4d54105604
--- a/libraries/AP_NavEKF3/derivation/main.py
+++ b/libraries/AP_NavEKF3/derivation/main.py
@@ -1,3 +1,4 @@
+#!/usr/bin/env python3
 # Copied from https://github.com/PX4/ecl/commit/264c8c4e8681704e4719d0a03b848df8617c0863
 # and modified for ArduPilot
 from sympy import *