diff --git a/neutron/values.yaml b/neutron/values.yaml
index a6aaae27da..e5bb6d8f07 100644
--- a/neutron/values.yaml
+++ b/neutron/values.yaml
@@ -1579,7 +1579,8 @@ conf:
         firewall_driver: neutron.agent.firewall.NoopFirewallDriver
       sriov_nic:
         physical_device_mappings: physnet2:enp3s0f1
-        exclude_devices: null
+        # NOTE: do not use null here, use an empty string
+        exclude_devices: ""
   dhcp_agent:
     DEFAULT:
       #(NOTE)portdirect: if unset this is populated dyanmicly from the value in