not a Mach-O file

From 2007 archive of the AMBER mail reflector:

Starting installation of Amber9 (serial) at Wed Oct 17 18:30:45 PDT 2007.
cd lib; make install
g95    -o new2oldparm new2oldparm.o nxtsec.o
ld: new2oldparm.o bad magic number (not a Mach-O file)
ld: nxtsec.o bad magic number (not a Mach-O file)
make[1]: *** [new2oldparm] Error 1

or in 2006

Starting installation of Amber8 (serial) at Mon Mar 27 14:42:01 EST 2006.
mkdir ../exe
mkdir: ../exe: File exists
make: [serial] Error 1 (ignored)
cd lib; make install
xlf90 -qextname=ddot:fdate:flush:lsame:dscal:dnrm2:idamax:drot:dswap:dspmv:daxpy:\
dspr2:dgemm:dcopy:dgemv:dtrmv:dtrmm:dger:lsame:dspev:dgeev:dspevd:dsyev:dppsv:\
dspsv:dlamch:dsteqr:dgeqr2:dorm2r:dlacpy:dlarnv:dlascl:dlaset:dlartg:dlanst:dlaev2:dlapy2:\
dlasr     -o new2oldparm new2oldparm.o nxtsec.o
/usr/bin/ld: new2oldparm.o bad magic number (not a Mach-O file)
/usr/bin/ld: nxtsec.o bad magic number (not a Mach-O file)
make[1]: *** [new2oldparm] Error 1
make: *** [serial] Error 2

This error is more likely due to the existing old *.o files from other computer. Please always do a

make clean

before you start to compile.