diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-06-30-04-44-29.bpo-41100.PJwA6F.rst b/Misc/NEWS.d/next/Core and Builtins/2020-06-30-04-44-29.bpo-41100.PJwA6F.rst
new file mode 100644
index 00000000000000..d6176d69f0eb0a
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-06-30-04-44-29.bpo-41100.PJwA6F.rst	
@@ -0,0 +1 @@
+add arm64 to the allowable Mac OS arches in mpdecimal.h
\ No newline at end of file
diff --git a/Modules/_decimal/libmpdec/mpdecimal.h b/Modules/_decimal/libmpdec/mpdecimal.h
index 108b76efa85941..35ce429f60124a 100644
--- a/Modules/_decimal/libmpdec/mpdecimal.h
+++ b/Modules/_decimal/libmpdec/mpdecimal.h
@@ -127,6 +127,9 @@ const char *mpd_version(void);
   #elif defined(__x86_64__)
     #define CONFIG_64
     #define ASM
+  #elif defined(__arm64__)
+    #define CONFIG_64
+    #define ANSI
   #else
     #error "unknown architecture for universal build."
   #endif