diff --git a/openapi.yaml b/openapi.yaml
index 4444304a..e3eeaa36 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -25,6 +25,11 @@ components:
       description: Content Identifier as specified at https://github.com/multiformats/cid
       example: QmYyQSo1c1Ym7orWxLYvCrM2EmxFTANf8wXmmE7DWjhx5N
 
+    SlotId:
+      type: string
+      description: Keccak hash of the abi encoded tuple (RequestId, slot index)
+      example: 268a781e0db3f7cf36b18e5f4fdb7f586ec9edd08e5500b17c0e518a769f114a
+
     LogLevel:
       type: string
       description: "One of the log levels: TRACE, DEBUG, INFO, NOTICE, WARN, ERROR or FATAL"
@@ -120,8 +125,7 @@ components:
       type: object
       properties:
         id:
-          type: string
-          description: Slot ID
+          $ref: "#/components/schemas/SlotId"
         request:
           $ref: "#/components/schemas/StorageRequest"
         slotIndex:
@@ -407,6 +411,13 @@ paths:
       summary: "Returns active slot with id {slotId} for the host"
       tags: [ Marketplace ]
       operationId: getActiveSlotById
+      parameters:
+        - in: path
+          name: slotId
+          required: true
+          schema:
+            $ref: "#/components/schemas/Cid"
+          description: File to be downloaded.
       responses:
         "200":
           description: Retrieved active slot