diff --git a/lib/Cake/Network/CakeResponse.php b/lib/Cake/Network/CakeResponse.php
index 2f60667fe47..70fbf554044 100644
--- a/lib/Cake/Network/CakeResponse.php
+++ b/lib/Cake/Network/CakeResponse.php
@@ -1281,7 +1281,7 @@ public function file($path, $options = array()) {
 			$agent = env('HTTP_USER_AGENT');
 
 			if (preg_match('%Opera(/| )([0-9].[0-9]{1,2})%', $agent)) {
-				$contentType = 'application/octetstream';
+				$contentType = 'application/octet-stream';
 			} elseif (preg_match('/MSIE ([0-9].[0-9]{1,2})/', $agent)) {
 				$contentType = 'application/force-download';
 			}