I was getting the following error when compiling SpamAssassin.

Makefile:94: *** missing separator.  Stop.

Googling around I found lots of people had this problem. It's related to the language that you tell Perl you have. The fix is pretty simple however, you just have to tell Perl to use US english instead of en_US.UTF-8. After that everything works just fine and my SpamAssassin is updated to 2.64!

export LANG=en_US
perl Makefile.PL
make
make install