diff --git a/rpi/clone b/rpi/clone
index 6b4267f..eb375b3 100755
--- a/rpi/clone
+++ b/rpi/clone
@@ -17,7 +17,7 @@ def boxkind():
     return sysclass[0] if sysclass else 'rpi'
 
 HOST = "l_samenv@linse-c"
-SUBDIR = "boxes/{boxkind()}_images"
+SUBDIR = f"boxes/{boxkind()}_images"
 DEFDEST = f"{HOST}:{SUBDIR}"
 file = f"{time.strftime('%Y-%m-%d')}.lz4"