diff --git a/api/v1/swagger/definitions/ill_request.yaml b/api/v1/swagger/definitions/ill_request.yaml
index 7c668bdfb5..2c585d0be5 100644
--- a/api/v1/swagger/definitions/ill_request.yaml
+++ b/api/v1/swagger/definitions/ill_request.yaml
@@ -24,7 +24,9 @@ properties:
     type: string
     description: Internal library identifier
   requested_date:
-    type: string
+    type:
+      - string
+      - "null"
     format: date
     description: Date the request was placed by the patron
   replied_date: