diff --git a/ChangeLog b/ChangeLog
index 5441f6142b..876fc15290 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2012-05-19  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* sysdeps/x86_64/x32/_itoa.h: Add comment.
+
 2012-05-19  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/powerpc/soft-fp/Makefile: Remove file.
diff --git a/sysdeps/x86_64/x32/_itoa.h b/sysdeps/x86_64/x32/_itoa.h
index f9ec802726..0f9ed47726 100644
--- a/sysdeps/x86_64/x32/_itoa.h
+++ b/sysdeps/x86_64/x32/_itoa.h
@@ -1,3 +1,4 @@
+/* X32 uses 64-bit _itoa_word and _itoa is mapped to _itoa_word.  */
 #define _ITOA_NEEDED		0
 #define _ITOA_WORD_TYPE		unsigned long long int
 #include_next <_itoa.h>