diff --git a/firmware/Makefile b/firmware/Makefile
index 54705d1c..5e89d2ab 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -25,7 +25,7 @@ PATH_BASEBAND=baseband
 
 # TODO: Pass these (as #defines?) to Makefiles, use values in code.
 PAD_BOOTSTRAP=0x10000
-PAD_HACKRF_FIRMWARE=0x10000
+PAD_HACKRF_FIRMWARE=65536
 PAD_BASEBAND=0x20000
 
 TARGET=portapack-h1-firmware
@@ -64,8 +64,8 @@ $(TARGET_BOOTSTRAP)_pad.bin: $(TARGET_BOOTSTRAP).elf
 
 $(TARGET_HACKRF_FIRMWARE)_dfu_pad.bin: $(TARGET_HACKRF_FIRMWARE).dfu
 	# TODO: Not confident this is reliable. It certainly won't work on Windows.
-	cp $(TARGET_HACKRF_FIRMWARE).dfu $(TARGET_HACKRF_FIRMWARE)_dfu_pad.bin
-	dd if=/dev/null of=$(TARGET_HACKRF_FIRMWARE)_dfu_pad.bin bs=1 count=1 seek=$(PAD_HACKRF_FIRMWARE)
+	# Pad the .dfu with zeros, then truncate to the desired length.
+	head -c $(PAD_HACKRF_FIRMWARE) /dev/zero | cat $(TARGET_HACKRF_FIRMWARE).dfu - | head -c $(PAD_HACKRF_FIRMWARE) >$(TARGET_HACKRF_FIRMWARE)_dfu_pad.bin
 
 $(TARGET_BASEBAND)_pad.bin: $(TARGET_BASEBAND).elf
 	$(CP) -O binary --pad-to $(PAD_BASEBAND) $(TARGET_BASEBAND).elf $(TARGET_BASEBAND)_pad.bin