--- a/python/mozbuild/mozbuild/configure/constants.py
+++ b/python/mozbuild/mozbuild/configure/constants.py
@@ -71,17 +71,17 @@ WindowsBinaryType = EnumString.subclass(
     'win64',
 )
 
 # The order of those checks matter
 CPU_preprocessor_checks = OrderedDict((
     ('x86', '__i386__ || _M_IX86'),
     ('x86_64', '__x86_64__ || _M_X64'),
     ('arm', '__arm__ || _M_ARM'),
-    ('aarch64', '__aarch64__'),
+    ('aarch64', '__aarch64__ || _M_ARM64'),
     ('ia64', '__ia64__'),
     ('s390x', '__s390x__'),
     ('s390', '__s390__'),
     ('ppc64', '__powerpc64__'),
     ('ppc', '__powerpc__'),
     ('Alpha', '__alpha__'),
     ('hppa', '__hppa__'),
     ('sparc64', '__sparc__ && __arch64__'),