diff --git a/ChangeLog b/ChangeLog
index 50bbb8dbbf..6dbd1b59f2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Aug 23 16:02:20 2012  Koichi Sasada  <ko1@atdot.net>
+
+	* ext/date/depend: add dependency to $(ruby_headers).
+
 Thu Aug 23 12:51:39 2012  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* insns.def (invokesuper): reverted r36640 partially to make super
diff --git a/ext/date/depend b/ext/date/depend
index 7e5d62e79d..43d5d7e61f 100644
--- a/ext/date/depend
+++ b/ext/date/depend
@@ -1,2 +1,2 @@
-date_core.o: date_tmx.h
-date_strftime.o: date_tmx.h
+date_core.o: date_tmx.h $(ruby_headers)
+date_strftime.o: date_tmx.h $(ruby_headers)