Compaling fails on MacOS

[gecbla]

Trying to compile with make trigger following error

cc  -I/usr/local/opt/icu4c/include -L/usr/local/opt/icu4c/lib  tcp-send-test.c   -o tcp-send-test
In file included from tcp-send-test.c:13:
./util.h:17:41: warning: format specifies type 'long' but the argument has type '__darwin_suseconds_t' (aka 'int') [-Wformat]
        printf("[%-.8ld.%-.6ld] ",  tv.tv_sec, tv.tv_usec);
                        ~~~~~~                 ^~~~~~~~~~
                        %-.6d
1 warning generated.
cc  -I/usr/local/opt/icu4c/include -L/usr/local/opt/icu4c/lib  tcp-recv-test.c   -o tcp-recv-test
In file included from tcp-recv-test.c:15:
./util.h:17:41: warning: format specifies type 'long' but the argument has type '__darwin_suseconds_t' (aka 'int') [-Wformat]
        printf("[%-.8ld.%-.6ld] ",  tv.tv_sec, tv.tv_usec);
                        ~~~~~~                 ^~~~~~~~~~
                        %-.6d
1 warning generated.
cc  -I/usr/local/opt/icu4c/include -L/usr/local/opt/icu4c/lib  tcp-keepalive-test.c   -o tcp-keepalive-test
In file included from tcp-keepalive-test.c:13:
./util.h:17:41: warning: format specifies type 'long' but the argument has type '__darwin_suseconds_t' (aka 'int') [-Wformat]
        printf("[%-.8ld.%-.6ld] ",  tv.tv_sec, tv.tv_usec);
                        ~~~~~~                 ^~~~~~~~~~
                        %-.6d
1 warning generated.

make: 3.81
Mac OS: 10.14.6