diff --git a/docs/device/usb.md b/docs/device/usb.md
index cc4a9595..ae5d8c89 100644
--- a/docs/device/usb.md
+++ b/docs/device/usb.md
@@ -117,7 +117,7 @@ Select the file and drag and drop it onto your `MICROBIT` drive.
 
 ![](/static/mb/device/usb-osx-firefox-1.jpg)
 
-![](/static/mb/device/usb-osx-firefox-2.jpg)
+![](/static/mb/device/usb-osx-firefox-2.png)
 
 #### Chrome
 
diff --git a/pxtarget.json b/pxtarget.json
index f7d9bd73..84a02977 100644
--- a/pxtarget.json
+++ b/pxtarget.json
@@ -284,7 +284,7 @@
                 "name": "save",
                 "os": "mac",
                 "browser": "firefox",
-                "path": "/static/mb/device/usb-osx-firefox-1.png"
+                "path": "/static/mb/device/usb-osx-firefox-1.jpg"
             },
             {
                 "name": "save",