all: dccpping
-dccpping: dccpping.c
- ${CC} ${CFLAGS} ${LDLIBS} dccpping.c -odccpping
+dccpping: dccpping.c checksums.h checksums.o Makefile
+ ${CC} ${CFLAGS} ${LDLIBS} dccpping.c checksums.o -odccpping
+
+checksums.o: checksums.c checksums.h Makefile
+ ${CC} ${CFLAGS} ${LDLIBS} -c checksums.c -ochecksums.o
install: dccpping