Or may be better to use explicit alignment 8 if this is 32-bit platform.

diff -r a417d89fbc38 Python/pyhash.c
--- a/Python/pyhash.c   Thu Mar 26 09:37:23 2015 +0100
+++ b/Python/pyhash.c   Fri Mar 27 12:02:55 2015 +0200
@@ -247,7 +247,7 @@ fnv(const void *src, Py_ssize_t len)
     union {
         Py_uhash_t value;
         unsigned char bytes[SIZEOF_PY_UHASH_T];
-    } block;
+    } block __attribute__ ((__aligned__(8)));
 
 #ifdef Py_DEBUG
     assert(_Py_HashSecret_Initialized);