diff --git a/src/index.ts b/src/index.ts
index fa92fb7..29c1fba 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -192,8 +192,8 @@ function teenyRequest(
   const multipart = reqOpts.multipart as RequestPart[];
   if (reqOpts.multipart && multipart.length === 2) {
     if (!callback) {
-      console.error('multipart without callback not implemented.');
-      return;
+      // TODO: add support for multipart uploads through streaming
+      throw new Error('Multipart without callback is not implemented.');
     }
     const boundary: string = uuid.v4();
     (options.headers as Headers)[