diff --git a/lib/Controller/FolderController.php b/lib/Controller/FolderController.php
index 2182a0bea..ec82dd7e4 100644
--- a/lib/Controller/FolderController.php
+++ b/lib/Controller/FolderController.php
@@ -100,7 +100,7 @@ private function formatFolder(array $folder): array {
 	 * Gets all Groupfolders
 	 * @NoAdminRequired
 	 * @param bool $applicable Filter by applicable groups
-	 * @return DataResponse<Http::STATUS_OK, list<GroupFoldersFolder>, array{}>
+	 * @return DataResponse<Http::STATUS_OK, array<string, GroupFoldersFolder>, array{}>
 	 * @throws OCSNotFoundException Storage not found
 	 *
 	 * 200: Groupfolders returned
@@ -111,8 +111,11 @@ public function getFolders(bool $applicable = false): DataResponse {
 			throw new OCSNotFoundException();
 		}
 
-		$folders = array_values($this->manager->getAllFoldersWithSize($storageId));
-		$folders = array_map($this->formatFolder(...), $folders);
+		$folders = [];
+		foreach ($this->manager->getAllFoldersWithSize($storageId) as $id => $folder) {
+			// Make them string-indexed for OpenAPI JSON output
+			$folders[(string)$id] = $this->formatFolder($folder);
+		}
 		$isAdmin = $this->delegationService->isAdminNextcloud() || $this->delegationService->isDelegatedAdmin();
 		if ($isAdmin && !$applicable) {
 			return new DataResponse($folders);
@@ -121,7 +124,7 @@ public function getFolders(bool $applicable = false): DataResponse {
 			$folders = $this->foldersFilter->getForApiUser($folders);
 		}
 		if ($applicable || !$this->delegationService->hasApiAccess()) {
-			$folders = array_values(array_filter(array_map($this->filterNonAdminFolder(...), $folders)));
+			$folders = array_filter(array_map($this->filterNonAdminFolder(...), $folders));
 		}
 		return new DataResponse($folders);
 	}
diff --git a/lib/Service/FoldersFilter.php b/lib/Service/FoldersFilter.php
index 99df216c3..d13c52133 100644
--- a/lib/Service/FoldersFilter.php
+++ b/lib/Service/FoldersFilter.php
@@ -24,8 +24,8 @@ public function __construct(IUserSession $userSession, IGroupManager $groupManag
 	}
 
 	/**
-	 * @param list<GroupFoldersFolder> $folders List of all folders
-	 * @return list<GroupFoldersFolder>
+	 * @param GroupFoldersFolder[] $folders List of all folders
+	 * @return GroupFoldersFolder[]
 	 */
 	public function getForApiUser(array $folders): array {
 		$user = $this->userSession->getUser();
diff --git a/openapi.json b/openapi.json
index ab42e83b4..bd7ec2fe1 100644
--- a/openapi.json
+++ b/openapi.json
@@ -248,8 +248,8 @@
                         "content": {
                             "application/json": {
                                 "schema": {
-                                    "type": "array",
-                                    "items": {
+                                    "type": "object",
+                                    "additionalProperties": {
                                         "$ref": "#/components/schemas/Folder"
                                     }
                                 }
diff --git a/src/types/openapi/openapi.ts b/src/types/openapi/openapi.ts
index eab4ebb6a..daa2a5bc1 100644
--- a/src/types/openapi/openapi.ts
+++ b/src/types/openapi/openapi.ts
@@ -328,7 +328,9 @@ export interface operations {
                     [name: string]: unknown;
                 };
                 content: {
-                    "application/json": components["schemas"]["Folder"][];
+                    "application/json": {
+                        [key: string]: components["schemas"]["Folder"];
+                    };
                 };
             };
             /** @description Storage not found */