diff --git a/ChangeLog b/ChangeLog
index 6272417262..a273177a73 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Thu Apr 11 06:15:51 2013  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* regint.h: fix typo: _M_AMD86 -> _M_AMD64.
+
+	* siphash.c: ditto.
+
+	* st.c: ditto.
+
 Thu Apr 11 06:09:57 2013  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/fiddle/extconf.rb: define RUBY_LIBFFI_MODVERSION macro.
diff --git a/regint.h b/regint.h
index 00d947a5b7..9192a67fde 100644
--- a/regint.h
+++ b/regint.h
@@ -49,7 +49,7 @@
 #endif
 
 #if defined(__i386) || defined(__i386__) || defined(_M_IX86) || \
-    defined(__x86_64) || defined(__x86_64__) || defined(_M_AMD86) || \
+    defined(__x86_64) || defined(__x86_64__) || defined(_M_AMD64) || \
     defined(__mc68020__)
 #define PLATFORM_UNALIGNED_WORD_ACCESS
 #endif
diff --git a/siphash.c b/siphash.c
index c100b14ee7..2018ade431 100644
--- a/siphash.c
+++ b/siphash.c
@@ -29,7 +29,7 @@
 
 #ifndef UNALIGNED_WORD_ACCESS
 # if defined(__i386) || defined(__i386__) || defined(_M_IX86) || \
-     defined(__x86_64) || defined(__x86_64__) || defined(_M_AMD86) || \
+     defined(__x86_64) || defined(__x86_64__) || defined(_M_AMD64) || \
      defined(__mc68020__)
 #   define UNALIGNED_WORD_ACCESS 1
 # endif
diff --git a/st.c b/st.c
index c5550bc673..eaed209886 100644
--- a/st.c
+++ b/st.c
@@ -1242,7 +1242,7 @@ strhash(st_data_t arg)
 
 #ifndef UNALIGNED_WORD_ACCESS
 # if defined(__i386) || defined(__i386__) || defined(_M_IX86) || \
-     defined(__x86_64) || defined(__x86_64__) || defined(_M_AMD86) || \
+     defined(__x86_64) || defined(__x86_64__) || defined(_M_AMD64) || \
      defined(__mc68020__)
 #   define UNALIGNED_WORD_ACCESS 1
 # endif