diff --git a/README.md b/README.md
index 221263d..1c29fde 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ There are several options for flashing Thermostat. DFU requires only a micro-USB
 
 ### dfu-util on Linux
 * Install the DFU USB tool (dfu-util).
-* Convert firmware from ELF to BIN: `arm-none-eabi-objcopy -O binary thermostat thermostat.bin` (you can skip this step if using the BIN from Hydra)
+* Convert firmware from ELF to BIN: `arm-none-eabi-objcopy -O binary target/thumbv7em-none-eabihf/release/thermostat thermostat.bin` (you can skip this step if using the BIN from Hydra)
 * Connect to the Micro USB connector to Thermostat below the RJ45.
 * Add jumper to Thermostat v2.0 across 2-pin jumper adjacent to JTAG connector.
 * Cycle board power to put it in DFU update mode
diff --git a/flake.nix b/flake.nix
index 803e774..d7329c7 100644
--- a/flake.nix
+++ b/flake.nix
@@ -39,7 +39,7 @@
           };
         };
 
-        nativeBuildInputs = [ pkgs.llvm ];
+        nativeBuildInputs = [ pkgs.gcc-arm-embedded ];
 
         buildPhase = ''
           cargo build --release --bin thermostat
@@ -49,7 +49,7 @@
           mkdir -p $out $out/nix-support
           cp target/thumbv7em-none-eabihf/release/thermostat $out/thermostat.elf
           echo file binary-dist $out/thermostat.elf >> $out/nix-support/hydra-build-products
-          llvm-objcopy -O binary target/thumbv7em-none-eabihf/release/thermostat $out/thermostat.bin
+          arm-none-eabi-objcopy -O binary target/thumbv7em-none-eabihf/release/thermostat $out/thermostat.bin
           echo file binary-dist $out/thermostat.bin >> $out/nix-support/hydra-build-products
         '';
 
@@ -67,7 +67,8 @@
       devShell.x86_64-linux = pkgs.mkShell {
         name = "thermostat-dev-shell";
         buildInputs = with pkgs; [
-          rust openocd dfu-util
+          rust gcc-arm-embedded
+          openocd dfu-util
           ] ++ (with python3Packages; [
             numpy matplotlib
           ]);