diff --git a/modules/flashable.nix b/modules/flashable.nix
index 1fdeff0..faf224d 100644
--- a/modules/flashable.nix
+++ b/modules/flashable.nix
@@ -56,7 +56,7 @@ in {
           setenv serverip ${tftp.serverip}
           setenv ipaddr ${tftp.ipaddr}
           tftp 0x$(printf %x ${tftp.loadAddress}) result/firmware.bin
-          erase 0x$(printf %x ${flash.address}) +0x$(printf %x ${flash.size})
+          erase 0x$(printf %x ${flash.address}) +\''${filesize})
           cp.b 0x$(printf %x ${tftp.loadAddress}) 0x$(printf %x ${flash.address}) \''${filesize}
           echo command line was ${builtins.toJSON (concatStringsSep " " config.boot.commandLine)}
           EOF