diff --git a/autoca/certutil.py b/autoca/certutil.py
index 4048a2480d9acec767b21183119b1b6990bec2e1..73e17116c7e16763b8cb6a791e6f3498e5564825 100644
--- a/autoca/certutil.py
+++ b/autoca/certutil.py
@@ -44,6 +44,7 @@ def sign_certificate(req, ca_key, ca_crt, serial_num, days,
     cert.set_subject(req.get_subject())
     cert.set_pubkey(req.get_pubkey())
     if extensions:
+        cert.set_version(3)
         cert.add_extensions(extensions)
     cert.sign(ca_key, digest)
     return cert