(let* ((gnu-phases (@ (guix build gnu-build-system) %standard-phases)))
       (modify-phases %standard-phases
         (add-before 'build 'configure
           (lambda* (#:key outputs #:allow-other-keys)
             (let* ((out (assoc-ref outputs "out"))
                    (bin (string-append out "/bin"))
                    (man1 (string-append out "/share/man/man1")))
               (mkdir-p bin)
               (mkdir-p man1)
               (substitute* "Makefile"
                 (("/usr/bin") bin)
                 (("/usr/share/man/man1") man1)
                 (("all: codecheck test") "all: mnexec")
                 (("cc") "gcc")
                 (("python setup\\.py install") ":"))
               (substitute* "mininet/node.py"
                 (("'mnexec'") (string-append "'" bin "/mnexec'")))
               #t)))
         (add-before 'build 'build-mnexec
           (assoc-ref gnu-phases 'build))
         (add-before 'install 'install-mnexec
           (assoc-ref gnu-phases 'install))))