diff --git a/doc/gendoc.py b/doc/gendoc.py
old mode 100644
new mode 100755
--- a/doc/gendoc.py
+++ b/doc/gendoc.py
@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 """usage: %s DOC ...
 
 where DOC is the name of a document