Should I worry about these compile warnings?

[Sid Wilroy]

maildirwatch.c:62: warning: return type of `main' is not `int'
./load maildirwatch hfield.o headerbody.o maildir.o \
prioq.o now.o getln.a env.a open.a strerr.a stralloc.a \
alloc.a substdio.a error.a str.a

idedit.c:124: warning: return type of `main' is not `int'
./load idedit strerr.a substdio.a error.a str.a fs.a \
wait.a open.a seek.a

install.c:156: warning: return type of `main' is not `int'
./load install-big fifo.o install.o auto_qmail.o \
auto_split.o auto_uids.o strerr.a substdio.a open.a error.a \
str.a fs.a