diff --git a/api-ref/source/parameters.yaml b/api-ref/source/parameters.yaml
index 093bb88e7b..31d5ca2561 100644
--- a/api-ref/source/parameters.yaml
+++ b/api-ref/source/parameters.yaml
@@ -2817,6 +2817,13 @@ lock:
   in: body
   required: true
   type: string
+locked:
+  description: |
+    True if the instance is locked otherwise False.
+  in: body
+  required: true
+  type: boolean
+  min_version: 2.9
 mac_addr:
   description: |
     The MAC address.
diff --git a/api-ref/source/servers.inc b/api-ref/source/servers.inc
index 491e11754d..a58cccbfeb 100644
--- a/api-ref/source/servers.inc
+++ b/api-ref/source/servers.inc
@@ -523,6 +523,7 @@ Response
   - OS-EXT-SERV-ATTR:ramdisk_id: server_ramdisk_id
   - OS-EXT-SERV-ATTR:root_device_name: server_root_device_name
   - OS-EXT-SERV-ATTR:user_data: server_user_data
+  - locked: locked
 
 **Example List Servers Detailed**
 
@@ -609,6 +610,7 @@ Response
   - OS-EXT-SERV-ATTR:ramdisk_id: server_ramdisk_id
   - OS-EXT-SERV-ATTR:root_device_name: server_root_device_name
   - OS-EXT-SERV-ATTR:user_data: server_user_data
+  - locked: locked
 
 **Example Show Server Details**
 
@@ -702,6 +704,7 @@ Response
   - OS-EXT-SERV-ATTR:ramdisk_id: server_ramdisk_id
   - OS-EXT-SERV-ATTR:root_device_name: server_root_device_name
   - OS-EXT-SERV-ATTR:user_data: server_user_data
+  - locked: locked
 
 **Example Update server name**