diff --git a/Makefile b/Makefile
index 1f4c49d..481b73e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,57 +1,16 @@
-all:
+REQUIREMENTS = dd echo msp430-objcopy msp430-gcc mspdebug
 
-QUIET=@
+include Makefile.common
 
-orig_fw.hex:
+build/orig_fw.hex:
 	@echo "Reading Novatouch firmware to $@..."
 	$(QUIET)mspdebug rf2500 "hexout 0x8000 0xffff $@"
 
-build/orig_fw.bin: orig_fw.hex
+build/orig_fw.bin: build/orig_fw.hex
 	@echo "Converting ihex fw to binary blob..."
 	$(QUIET)mkdir -p build
 	$(QUIET)msp430-objcopy -I ihex -O binary $< $@
 
-build/section_isr.bin: build/orig_fw.bin
-	@echo "Create isr vectors binary..."
-	$(QUIET)dd if=$< of=$@ bs=1 skip=32736 count=32 status=none
-
-build/section_data.bin: build/orig_fw.bin
-	@echo "Create data section binary..."
-	$(QUIET)dd if=$< of=$@ bs=1 count=10112 status=none
-
-build/section_data_patch.bin: build/section_data.bin patch.py
-	@echo "Patching data section..."
-	$(QUIET)python patch.py $< $@
-
-# IDA friendly elf file
-build/main.o: build/section_data_patch.bin build/section_isr.bin
-	@echo "Create main.o..."
-	$(QUIET)msp430-objcopy -I binary -O elf32-msp430 -B msp430:430X \
-		--rename-section .data=.text,contents,code,alloc,load,readonly \
-		--change-section-address .data=0x8000 \
-		--add-section .vectors=build/section_isr.bin \
-		--set-section-flags .vectors=contents,alloc,load,readonly,code \
-		--change-section-address .vectors=0xffe0 \
-		--set-start 0x8000 build/section_data_patch.bin $@
-
-build/enter_bsl.o: shellcode/enter_bsl.c
-	@echo "Compiling shellcode..."
-	$(QUIET)msp430-gcc -Os -mmcu=msp430f5510 -c $< -o $@
-
-# The main.o is an relocatable elf which we convert to an actual elf
-# for IDA to like it. Also link in our own objects
-main.elf: build/main.o build/enter_bsl.o
-	@echo "Create main.elf..."
-	$(QUIET)msp430-gcc -O0 -mmcu=msp430f5510 \
-		-Wl,--section-start=.text=0x8000 \
-		-Wl,--section-start=.vectors=0xffe0 \
-		-Wl,--entry=0x9ca6 \
-		-nostdlib \
-		$^ -o $@
-
 .PHONY: flash
-flash: main.elf
+flash: build/main.elf
 	$(QUIET)mspdebug rf2500 "prog $<"
-
-clean:
-	rm *.o *.bin main.elf
diff --git a/Makefile.bsl b/Makefile.bsl
index 17f3e42..6f64601 100644
--- a/Makefile.bsl
+++ b/Makefile.bsl
@@ -1,59 +1,26 @@
-all:
+REQUIREMENTS = dd echo msp430-objcopy msp430-gcc python
 
-QUIET=@
+include Makefile.common
 
+# Create dummy fw hex ending with the same ISR vectors as the original
+# firmware. These vectors are used as password to the BSL. Password
+# needs to be specified to read out existing firmware.
 build/dummy_fw.hex:
 	@echo "Creating dummy hex file with supposed BSL password..."
+	$(QUIET)mkdir -p build
 	$(QUIET)dd if=/dev/zero of=build/dummy_fw.bin bs=32 count=2047 status=none
 	$(QUIET)echo -n 'ffffffffffff9483ffff9aa0ffffffffffffffffffffffffffff3a98ffffa69c' | xxd -r -p >> build/dummy_fw.bin
 	$(QUIET)msp430-objcopy -I binary -O ihex build/dummy_fw.bin $@
 
+# This step is a hit-or-miss, if the password is wrong the device will
+# erase itself as a security measure. If this happens you will be
+# stuck in BSL mode without firmware. Then you need to find the
+# original firwmare to recover the keyboard.
 build/orig_fw.bin: build/dummy_fw.hex
 	@echo "Reading Novatouch firmware to $@..."
 	$(QUIET)python -m msp430.bsl5.hid --upload=0x8000-0xffff -f bin \
 	-x 0x2504 --password $< -o $@
 
-build/section_isr.bin: build/orig_fw.bin
-	@echo "Create isr vectors binary..."
-	$(QUIET)dd if=$< of=$@ bs=1 skip=32736 count=32 status=none
-
-build/section_data.bin: build/orig_fw.bin
-	@echo "Create data section binary..."
-	$(QUIET)dd if=$< of=$@ bs=1 count=10112 status=none
-
-build/section_data_patch.bin: build/section_data.bin patch.py
-	@echo "Patching data section..."
-	$(QUIET)python patch.py $< $@
-
-# IDA friendly elf file
-build/main.o: build/section_data_patch.bin build/section_isr.bin
-	@echo "Create main.o..."
-	$(QUIET)msp430-objcopy -I binary -O elf32-msp430 -B msp430:430X \
-		--rename-section .data=.text,contents,code,alloc,load,readonly \
-		--change-section-address .data=0x8000 \
-		--add-section .vectors=build/section_isr.bin \
-		--set-section-flags .vectors=contents,alloc,load,readonly,code \
-		--change-section-address .vectors=0xffe0 \
-		--set-start 0x8000 build/section_data_patch.bin $@
-
-build/enter_bsl.o: shellcode/enter_bsl.c
-	@echo "Compiling shellcode..."
-	$(QUIET)msp430-gcc -Os -mmcu=msp430f5510 -c $< -o $@
-
-# The main.o is an relocatable elf which we convert to an actual elf
-# for IDA to like it. Also link in our own objects
-build/main.elf: build/main.o build/enter_bsl.o
-	@echo "Create main.elf..."
-	$(QUIET)msp430-gcc -O0 -mmcu=msp430f5510 \
-		-Wl,--section-start=.text=0x8000 \
-		-Wl,--section-start=.vectors=0xffe0 \
-		-Wl,--entry=0x9ca6 \
-		-nostdlib \
-		$^ -o $@
-
 .PHONY: flash
 flash: build/main.elf
 	$(QUIET)python -m msp430.bsl5.hid -e -r $<
-
-clean:
-	rm build/*
diff --git a/Makefile.common b/Makefile.common
new file mode 100644
index 0000000..d6a695f
--- /dev/null
+++ b/Makefile.common
@@ -0,0 +1,47 @@
+OK := $(foreach exec,$(REQUIREMENTS),\
+	$(if $(shell which $(exec)),,$(error "Cannot find '$(exec)' in PATH")))
+
+all:
+
+QUIET=@
+
+build/section_isr.bin: build/orig_fw.bin
+	@echo "Create isr vectors binary..."
+	$(QUIET)dd if=$< of=$@ bs=1 skip=32736 count=32 status=none
+
+build/section_data.bin: build/orig_fw.bin
+	@echo "Create data section binary..."
+	$(QUIET)dd if=$< of=$@ bs=1 count=10112 status=none
+
+build/section_data_patch.bin: build/section_data.bin patch.py
+	@echo "Patching data section..."
+	$(QUIET)python patch.py $< $@
+
+# IDA friendly elf file
+build/main.o: build/section_data_patch.bin build/section_isr.bin
+	@echo "Create main.o..."
+	$(QUIET)msp430-objcopy -I binary -O elf32-msp430 -B msp430:430X \
+		--rename-section .data=.text,contents,code,alloc,load,readonly \
+		--change-section-address .data=0x8000 \
+		--add-section .vectors=build/section_isr.bin \
+		--set-section-flags .vectors=contents,alloc,load,readonly,code \
+		--change-section-address .vectors=0xffe0 \
+		--set-start 0x8000 build/section_data_patch.bin $@
+
+build/enter_bsl.o: shellcode/enter_bsl.c
+	@echo "Compiling shellcode..."
+	$(QUIET)msp430-gcc -Os -mmcu=msp430f5510 -c $< -o $@
+
+# The main.o is an relocatable elf which we convert to an actual elf
+# for IDA to like it. Also link in our own objects
+build/main.elf: build/main.o build/enter_bsl.o
+	@echo "Create main.elf..."
+	$(QUIET)msp430-gcc -O0 -mmcu=msp430f5510 \
+		-Wl,--section-start=.text=0x8000 \
+		-Wl,--section-start=.vectors=0xffe0 \
+		-Wl,--entry=0x9ca6 \
+		-nostdlib \
+		$^ -o $@
+
+clean:
+	rm build/*