Update ChangeLog for 4.0.3.
diff --git a/ChangeLog b/ChangeLog
index b7381a5..e3b0a51 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,7 +4,9 @@
 
     https://github.com/jemalloc/jemalloc
 
-* 4.0.3 (XXX)
+* 4.0.3 (September 24, 2015)
+
+  This bugfix release continues the trend of xallocx() and heap profiling fixes.
 
   Bug fixes:
   - Fix xallocx(..., MALLOCX_ZERO) to zero all trailing bytes of large