diff --git a/configure.in b/configure.in
index 7e9b2b91..b1f9062b 100644
--- a/configure.in
+++ b/configure.in
@@ -95,6 +95,8 @@ fi
 
 AC_CHECK_HEADER(sys/signalfd.h, , AC_MSG_ERROR([signalfd required; glibc 2.9+ recommended]))
 
+AC_CHECK_SIZEOF(void *)
+
 AC_CHECK_HEADERS(getopt.h,,)
 AC_CHECK_HEADERS(stdint.h,,)
 
diff --git a/src/misc.c b/src/misc.c
index 41797941..ede86509 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -215,7 +215,7 @@ b64_decode(const char *b64)
  * as of 2010-01-03.
  */
 
-#if __WORDSIZE == 64 /* 64bit platforms */
+#if SIZEOF_VOID_P == 8 /* 64bit platforms */
 
 uint64_t
 murmur_hash64(const void *key, int len, uint32_t seed)
@@ -273,7 +273,7 @@ murmur_hash64(const void *key, int len, uint32_t seed)
   return h;
 }
 
-#elif __WORDSIZE == 32 /* 32bit platforms */
+#elif SIZEOF_VOID_P == 4 /* 32bit platforms */
 
 uint64_t
 murmur_hash64(const void *key, int len, uint32_t seed)