Evaluate command inside comparison in makefile [duplicate]

Question

I would like to check if Linux system is ubuntu inside Makefile. What I do is:

copy_files:
    if [ "$(head -n 1 /etc/lsb-release | cut -d '=' -f2)" = "Ubuntu" ]; then \
        echo "ubuntu"; \
    else \
        echo "not ubuntu"; \
    fi

But the above condition fails always, i.e. it always prints "not ubuntu" on an ubuntu machine. So What am I doing wrong?