diff --git a/README.md b/README.md
index 4686f01a..4e277a0a 100644
--- a/README.md
+++ b/README.md
@@ -671,7 +671,7 @@ type UploadFileItem = {
   name: string;       // Name of the file, if not defined then filename is used
   filename: string;   // Name of file
   filepath: string;   // Path to file
-  filetype: string;   // The mimetype of the file to be uploaded, if not defined it will get mimetype from `filepath` extension
+  filetype?: string;   // The mimetype of the file to be uploaded, if not defined it will get mimetype from `filepath` extension
 };
 ```
 
diff --git a/index.d.ts b/index.d.ts
index da3fa7de..4a30e8e6 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -85,7 +85,7 @@ type UploadFileItem = {
 	name: string // Name of the file, if not defined then filename is used
 	filename: string // Name of file
 	filepath: string // Path to file
-	filetype: string // The mimetype of the file to be uploaded, if not defined it will get mimetype from `filepath` extension
+	filetype?: string // The mimetype of the file to be uploaded, if not defined it will get mimetype from `filepath` extension
 }
 
 type UploadBeginCallbackResult = {