--- M2Crypto-0.31.0/setup.py
+++ M2Crypto-0.31.0/setup.py
@@ -164,6 +164,10 @@
             # For RedHat-based distros, the '-D__{arch}__' option for
             # Swig needs to be normalized, particularly on i386.
             mach = platform.machine().lower()
+            if 'CHOST' in os.environ:
+                chost = os.environ['CHOST'].split('-')
+                if len(chost) >= 3:
+                    mach = chost[0]
             if mach in ('i386', 'i486', 'i586', 'i686'):
                 arch = '__i386__'
             elif mach in ('ppc64', 'powerpc64', 'ppc64le', 'ppc64el'):