diff --git a/systemdeps.h b/systemdeps.h
index b4a1472..27906f7 100644
--- a/systemdeps.h
+++ b/systemdeps.h
@@ -120,7 +120,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
 #endif /* __APPLE__ || __linux__ || __sun__ || sun */
 
-#if defined(__arm__)
+#if defined(__arm__) || defined(__ARM__)
     #undef POST_PACKED_STRUCTURE
     #define POST_PACKED_STRUCTURE
 #endif /* __arm__ */