diff --git a/ChangeLog b/ChangeLog
index a99a27beb6..03bc6072d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun May 27 10:02:33 2012  Tadayoshi Funaba  <tadf@dotrb.org>
+
+	* ext/date/date_strftime.c: allows %Ok and %Ol.
+
 Sun May 27 09:29:20 2012  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* ext/date/date_core.c: modified doc.
diff --git a/ext/date/date_strftime.c b/ext/date/date_strftime.c
index 4236666fa6..b162413b90 100644
--- a/ext/date/date_strftime.c
+++ b/ext/date/date_strftime.c
@@ -526,8 +526,7 @@ date_strftime_with_tmx(char *s, size_t maxsize, const char *format,
 	  case 'O':
 	    /* POSIX locale extensions, ignored for now */
 	    flags |= BIT_OF(LOCALE_O);
-	    if (*(format + 1) && strchr("deHImMSuUVwWy",
-					*(format + 1)))
+	    if (*(format + 1) && strchr("deHkIlmMSuUVwWy", *(format + 1)))
 		goto again;
 	    goto unknown;