diff --git a/AttachmentController.class.php b/AttachmentController.class.php
index 6688bff..4f66b76 100644
--- a/AttachmentController.class.php
+++ b/AttachmentController.class.php
@@ -125,7 +125,7 @@ public function action_upload()
 		// Set the allowed file types based on config.
 		$allowedFileTypes = C("plugin.Attachments.allowedFileTypes");
 		if (!empty($allowedFileTypes))
-			$uploader->allowedExtensions = $allowedFileTypes;
+			$uploader->allowedExtensions = explode(' ', $allowedFileTypes);
 
 		// Set the max file size based on config.
 		if ($size = C("plugin.Attachments.maxFileSize"))