fatal: more than one output file specified: arch/x86/start.o

Building Kernel
make -C ./kernel
make[1]: Entering directory '/home/peepers/How-to-Make-a-Computer-Operating-System/src/kernel'
nasm   -f elf -o  -c arch/x86/start.asm -o  arch/x86/start.o
arch/x86/start.asm: fatal: more than one output file specified: arch/x86/start.o

make[1]: *** [Makefile:64: arch/x86/start.o] Error 1
make[1]: Leaving directory '/home/peepers/How-to-Make-a-Computer-Operating-System/src/kernel'
make: *** [Makefile:11: all] Error 2