Errors with "make"

When trying to compile a small app, I get these errors, and I can't find out how to fix them.
Code:make[3]: Entering directory '/home/binkyd/Downloads/Alarm-Clock/alarm-clock-applet-0.3.4/src'
CC util.o
util.c: In function get_alarm_timestamp':
util.c:57:31: error: %c' yields only last 2 digits of year in some locales [-Werror=format-y2k]
57 | strftime (tmp, sizeof (tmp), "%c", tm);
| ^~~~
cc1: some warnings being treated as errors
make[3]: *** [Makefile:474: util.o] Error 1
make[3]: Leaving directory '/home/binkyd/Downloads/Alarm-Clock/alarm-clock-applet-0.3.4/src'
make[2]: *** [Makefile:494: all-recursive] Error 1
make[2]: Leaving directory '/home/binkyd/Downloads/Alarm-Clock/alarm-clock-applet-0.3.4/src'
make[1]: *** [Makefile:411: all-recursive] Error 1
make[1]: Leaving directory '/home/binkyd/Downloads/Alarm-Clock/alarm-clock-applet-0.3.4'
make: *** [Makefile:350: all] Error 2I've looked in the gcc manual and the man files etc but am lost.
Looking at Arch Pkgbuild hasn't helped yet, either.

Where do I find out what these are about so I can maybe fix it?