compilation error in madgraph

Hi all,
I have a model file which worked well on ubuntu. I just installed madgraph5 and updated its version on my new mac . I am getting a compilation error as follows. Can someone please help me .
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Error detected in "generate_events run_01"
write debug file /Users/Arjun/Desktop/pph1tt/run_01_tag_1_debug.log
If you need help with this issue please contact us on https://answers.launchpad.net/mg5amcnlo
MadGraph5Error : A compilation Error occurs when trying to compile /Users/Arjun/Desktop/pph1tt/Source.
 The compilation fails with the following output message:
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -c -o StringCast.o StringCast.f
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -c -o ranmar.o ranmar.f
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -c -o alfas_functions.o alfas_functions.f
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -c -o transpole.o transpole.f
     FATAL:/opt/local/bin/../libexec/as/x86_64/as: I don't understand 'm' flag!
     make: *** [transpole.o] Error 1
     make: *** Waiting for unfinished jobs....
     FATAL:/opt/local/bin/../libexec/as/x86_64/as: I don't understand 'm' flag!
     FATAL:/opt/local/bin/../libexec/as/x86_64/as: I don't understand 'm' flag!
     make: *** [StringCast.o] Error 1
     make: *** [alfas_functions.o] Error 1
     FATAL:/opt/local/bin/../libexec/as/x86_64/as: I don't understand 'm' flag!
     make: *** [ranmar.o] Error 1

 Please try to fix this compilations issue and retry.
 Help might be found at https://answers.launchpad.net/mg5amcnlo.
 If you think that this is a bug, you can report this at https://bugs.launchpad.net/mg5amcnlo
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Thanks in advance.