I'm trying to run the following sequence on ghc 6.4:

> ghc -fglasgow-exts --make Main

> ghc -o exec Main.o Exemplo1.o

But I always get this error message after the second command:
/usr/lib/ghc-6.4/libHSrts.a(Main.o)(.text+0xe): In function `main':
: undefined reference to `__stginit_ZCMain'
/usr/lib/ghc-6.4/libHSrts.a(Main.o)(.text+0x28): In function `main':
: undefined reference to `ZCMain_main_closure'
collect2: ld returned 1 exit status

Please, does anybody know what can I do to fix it?

Thanks