diff --git a/shell.nix b/shell.nix
index b3bcbe7..a2c586e 100644
--- a/shell.nix
+++ b/shell.nix
@@ -21,27 +21,16 @@ let
     '';
 
     openOCDFlashCustomised = writeShellScriptBin "openocd-flash-customised" ''
-        IFS='.|/' read -r a b c d e <<< $1
-        ((ip = (a << 32) + (b << 24) + (c << 16) + (d << 8) + e))
-        IFS=':' read -r a b c d e f <<< $2
-        ((mac = (16#$a << 40) + (16#$b << 32) + (16#$c << 24) + (16#$d << 16) + (16#$e << 8) + 16#$f))
-        IFS='.' read -r a b c d <<< $3
-        ((broker_ip = (a << 24) + (b << 16) + (c << 8) + d))
-        touch temp_name
-        printf "%s\x04" "$4" > temp_name
+        python3 flash.py $1 $2 $3 $4
         openocd -f openocd/openocd.cfg \
                 -c "init 
                     reset init 
                     halt 
                     stm32h7x mass_erase 1 
                     flash write_image erase target/thumbv7em-none-eabihf/release/humpback-dds 
-                    flash filld 0x08100000 $ip 1 
-                    flash filld 0x08100020 $mac 1 
-                    flash fillw 0x08100040 $broker_ip 1 
-                    flash write_image temp_name 0x08100060 bin
+                    flash write_image flash_config.bin 0x08100000 bin 
                     reset run 
                     shutdown"
-        rm temp_name
     '';
 
 in