--- setup.py.old	2010-02-12 20:35:12.208386376 +0000
+++ setup.py	2010-02-12 20:35:44.478260924 +0000
@@ -152,7 +152,7 @@
             self.compiler.include_dirs.insert(0, "src/inc-msvc/")
 
         # Detect libgmp and don't build _fastmath if it is missing.
-        lib_dirs = self.compiler.library_dirs + ['/lib', '/usr/lib']
+        lib_dirs = self.compiler.library_dirs + ['/lib', '/lib64', '/usr/lib', '/usr/lib64']
         if not (self.compiler.find_library_file(lib_dirs, 'gmp')):
             print >>sys.stderr, "warning: GMP library not found; Not building Crypto.PublicKey._fastmath."
             self.__remove_extensions(["Crypto.PublicKey._fastmath"])