diff --git a/rpi/write_to b/rpi/write_to
index eff0a54..59fe3e6 100755
--- a/rpi/write_to
+++ b/rpi/write_to
@@ -163,7 +163,7 @@ class Darwin(HostSystem):
             prt('unmount bootfs')
             os.system('diskutil unmount bootfs')
         lines = []
-        with Popen(['rpiboot'], stdout=PIPE) as p:
+        with Popen(['rpiboot', '-d', 'mass-storage-gadget64'], stdout=PIPE) as p:
             tmo = 1
             t = 0
             while select([p.stdout], [], [], tmo)[0]: