diff --git a/packages/backend/src/server/api/call.ts b/packages/backend/src/server/api/call.ts
index ea457d9556..e767b15417 100644
--- a/packages/backend/src/server/api/call.ts
+++ b/packages/backend/src/server/api/call.ts
@@ -78,8 +78,8 @@ export default async (endpoint: string, user: User | null | undefined, token: Ac
 	}
 
 	// Cast non JSON input
-	if (ep.meta.requireFile) {
-		for (const k of Object.keys(ep.params)) {
+	if (ep.meta.requireFile && ep.params.properties) {
+		for (const k of Object.keys(ep.params.properties)) {
 			const param = ep.params.properties![k];
 			if (['boolean', 'number', 'integer'].includes(param.type ?? '') && typeof data[k] === 'string') {
 				try {
diff --git a/packages/backend/src/server/api/endpoints/drive/files/create.ts b/packages/backend/src/server/api/endpoints/drive/files/create.ts
index f5791f6ec7..aafb650dd7 100644
--- a/packages/backend/src/server/api/endpoints/drive/files/create.ts
+++ b/packages/backend/src/server/api/endpoints/drive/files/create.ts
@@ -35,7 +35,7 @@ export const meta = {
 	},
 } as const;
 
-const paramDef = {
+export const paramDef = {
 	type: 'object',
 	properties: {
 		folderId: { type: 'string', format: 'misskey:id', nullable: true, default: null },