diff --git a/main.js b/main.js
index 66c9b01..6293f7b 100644
--- a/main.js
+++ b/main.js
@@ -30,7 +30,7 @@ function File (options) {
 
   this.buffering = true
 
-  this.mimetype = mimetypes.lookup(this.path.slice(this.path.lastIndexOf('.')+1))
+  this.mimetype = options.mimetype || mimetypes.lookup(this.path.slice(this.path.lastIndexOf('.')+1))
 
   var stopBuffering = function () {
     self.buffering = false