diff --git a/modules/outputs/tftpboot.nix b/modules/outputs/tftpboot.nix
index 87ae34f..aaeb936 100644
--- a/modules/outputs/tftpboot.nix
+++ b/modules/outputs/tftpboot.nix
@@ -72,8 +72,7 @@ in {
             rootfsStart=$(printf %x $((${toString cfg.loadAddress} + 0x100000 + $uimageSize   &(~0xfffff) )))
             rootfsBytes=$(($(stat -L -c %s ${o.rootfs}) + 0x100000 &(~0xfffff)))
             rootfsBytes=$(($rootfsBytes + ${toString cfg.freeSpaceBytes} ))
-            rootfsMb=$(($rootfsBytes >> 20))
-            cmd="mtdparts=phram0:''${rootfsMb}M(rootfs) phram.phram=phram0,0x''${rootfsStart},''${rootfsBytes},${toString config.hardware.flash.eraseBlockSize} root=/dev/mtdblock0";
+            cmd="mtdparts=phram0:''${rootfsBytes}(rootfs) phram.phram=phram0,0x''${rootfsStart},''${rootfsBytes},${toString config.hardware.flash.eraseBlockSize} root=/dev/mtdblock0";
 
             dtbStart=$(printf %x $((${toString cfg.loadAddress} + $rootfsBytes + 0x100000 + $uimageSize )))