diff --git a/vmm/src/api/openapi/cloud-hypervisor.yaml b/vmm/src/api/openapi/cloud-hypervisor.yaml
index 949e30d6d..e2bc83d0d 100644
--- a/vmm/src/api/openapi/cloud-hypervisor.yaml
+++ b/vmm/src/api/openapi/cloud-hypervisor.yaml
@@ -497,6 +497,9 @@ components:
         balloon:
           type: boolean
           default: false
+        balloon_size:
+          type: integer
+          format: uint64
         zones:
           type: array
           items: