diff -r a858cde113f2 Modules/_ctypes/cfield.c
--- a/Modules/_ctypes/cfield.c	Sat Jan 24 19:26:18 2015 -0800
+++ b/Modules/_ctypes/cfield.c	Sun Jan 25 19:29:01 2015 +0100
@@ -765,6 +765,7 @@
     if (get_ulong(value, &val) < 0)
         return  NULL;
     memcpy(&field, ptr, sizeof(field));
+    field = SWAP_INT(field);
     field = SET(unsigned int, field, (unsigned int)val, size);
     field = SWAP_INT(field);
     memcpy(ptr, &field, sizeof(field));