diff --git a/quark/api/extensions/subnets_quark.py b/quark/api/extensions/subnets_quark.py
index cabf4a3..2994e9c 100644
--- a/quark/api/extensions/subnets_quark.py
+++ b/quark/api/extensions/subnets_quark.py
@@ -19,7 +19,7 @@ from neutron.api import extensions
 
 EXTENDED_ATTRIBUTES_2_0 = {
     'subnets': {
-        "segment_id": {"allow_post": True, "default": False},
+        "segment_id": {"allow_post": True, "default": None},
         "enable_dhcp": {'allow_post': False, 'allow_put': False,
                         'default': False,
                         'is_visible': True},