diff --git a/packages/arcgis-rest-portal/src/items/update.ts b/packages/arcgis-rest-portal/src/items/update.ts
index 4c9734479e..be13123673 100644
--- a/packages/arcgis-rest-portal/src/items/update.ts
+++ b/packages/arcgis-rest-portal/src/items/update.ts
@@ -133,6 +133,7 @@ export function updateItemResource(
     requestOptions.params = {
       file: requestOptions.resource,
       fileName: requestOptions.name,
+      resourcesPrefix: requestOptions.prefix,
       text: requestOptions.content,
       ...requestOptions.params
     };
diff --git a/packages/arcgis-rest-portal/test/items/update.test.ts b/packages/arcgis-rest-portal/test/items/update.test.ts
index 1229c457aa..1897565999 100644
--- a/packages/arcgis-rest-portal/test/items/update.test.ts
+++ b/packages/arcgis-rest-portal/test/items/update.test.ts
@@ -253,7 +253,8 @@ describe("search", () => {
       updateItemResource({
         id: "3ef",
         owner: "dbouwman",
-        name: "image/banner.png",
+        name: "banner.png",
+        prefix: "image",
         content: "jumbotron",
         ...MOCK_USER_REQOPTS
       })
@@ -267,7 +268,8 @@ describe("search", () => {
           const params = options.body as FormData;
           if (params.get) {
             expect(params.get("f")).toEqual("json");
-            expect(params.get("fileName")).toEqual("image/banner.png");
+            expect(params.get("fileName")).toEqual("banner.png");
+            expect(params.get("resourcesPrefix")).toEqual("image");
             expect(params.get("text")).toEqual("jumbotron");
             expect(params.get("access")).toEqual(null);
             expect(params.get("token")).toEqual("fake-token");