diff --git a/modules/flashimage.nix b/modules/flashimage.nix
index b5f0fe1..4e7675b 100644
--- a/modules/flashimage.nix
+++ b/modules/flashimage.nix
@@ -53,7 +53,7 @@ in {
           setenv serverip ${tftp.serverip}
           setenv ipaddr ${tftp.ipaddr}
           tftp 0x$(printf %x ${tftp.loadAddress}) result/firmware.bin
-          erase 0x$(printf %x ${flash.address}) +\''${filesize})
+          erase 0x$(printf %x ${flash.address}) +${flash.size}
           cp.b 0x$(printf %x ${tftp.loadAddress}) 0x$(printf %x ${flash.address}) \''${filesize}
           echo command line was ${builtins.toJSON (concatStringsSep " " config.boot.commandLine)}
           EOF