diff --git a/.cargo/config.toml b/.cargo/config.toml
index 5fe0add..e67a064 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -1,5 +1,5 @@
 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
-runner = "probe-rs run --chip nRF52840_xxAA"
+runner = "elf2uf2-rs -d"
 linker = "flip-link"
 
 [build]
@@ -7,4 +7,4 @@ target = "thumbv7em-none-eabihf"
 
 [env]
 DEFMT_LOG = "info"
-KEYBOARD_TOML_PATH =  { value = "keyboard.toml", relative = true }
+KEYBOARD_TOML_PATH = { value = "keyboard.toml", relative = true }
diff --git a/flake.nix b/flake.nix
index bb4ddf0..79ad2fa 100644
--- a/flake.nix
+++ b/flake.nix
@@ -59,6 +59,10 @@
         packages = with pkgs; [
           (crates.buildCrate "rmkit" {})
           (crates.buildCrate "cargo-hex-to-uf2" {})
+          (crates.buildCrate "elf2uf2-rs" {
+            buildInputs = with pkgs; [libudev-zero];
+            nativeBuildInputs = with pkgs; [pkg-config];
+          })
           flip-link
           cargo-make
           cargo-binutils
diff --git a/keyboard.toml b/keyboard.toml
index eadc0d5..4bd3f60 100644
--- a/keyboard.toml
+++ b/keyboard.toml
@@ -12,13 +12,13 @@ chip = "nrf52840"
 # row2col = true
 rows = 4
 cols = 12
-layers = 3
+layers = 4
 keymap = [
     [
         ["Tab", "Q", "W", "E", "R", "T", "Y", "U", "I", "O", "P", "Backspace"],
-        ["LCtrl", "A", "S", "D", "F", "G", "H", "J", "K", "L", "Semicolon", "Quote"],
+        ["MT(esc, l_ctrl)", "MT(A, l_gui)", "MT(S, l_alt)", "MT(D, l_shift)", "MT(F, l_ctrl)", "G", "H", "MT(J, r_ctrl)", "MT(K, r_shift)", "MT(L, r_alt)", "MT(Semicolon, r_gui)", "Quote"],
         ["LShift", "Z", "X", "C", "V", "B", "N", "M", "Comma", "Dot", "Slash", "Enter"],
-        ["__", "__", "__", "OSM(LGui)", "LAlt", "Space", "Enter", "MO(2)", "MO(1)", "__", "__", "__"]
+        ["__", "__", "__", "MO(2)", "MO(1)", "Space", "Enter", "MO(1)", "MO(2)", "__", "__", "__"]
     ],
     [
         ["Tab", "Kc1", "Kc2", "Kc3", "Kc4", "Kc5", "Kc6", "Kc7", "Kc8", "Kc9", "Kc0", "Delete"],
@@ -32,13 +32,19 @@ keymap = [
         ["_", "User10", "_", "_", "_", "_", "_", "_", "_", "_", "_", "_"],
         ["__", "__", "__", "_", "_", "_", "_", "_", "LAlt", "__", "__", "__"]
     ],
+    [
+        ["_", "WM(Kc1, LShift)", "WM(Kc2, LShift)", "WM(Kc3, LShift)", "WM(Kc4, LShift)", "WM(Kc5, LShift)", "WM(Kc6, LShift)", "WM(Kc7, LShift)", "WM(Kc8, LShift)", "WM(Kc9, LShift)", "WM(Kc0, LShift)", "Backspace"],
+        ["_", "User0", "User1", "User2", "User4", "User5", "Minus", "Equal", "LeftBracket", "RightBracket", "Backslash", "Grave"],
+        ["_", "User10", "_", "_", "_", "_", "_", "_", "_", "_", "_", "_"],
+        ["__", "__", "__", "_", "_", "_", "_", "_", "LAlt", "__", "__", "__"]
+    ],
 ]
 
 [ble]
 enabled = true
 
 [behavior]
-tap_hold = { enable_hrm = true }
+tap_hold = { enable_hrm = true, permissive_hold = true, hold_timeout = "200ms" }
 
 [split]
 connection = "ble"