diff --git a/ChangeLog b/ChangeLog
index d09fb5ece4..5418389a38 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-06-29  Rafal Luzynski  <digitalfreak@lingonborough.com>
+
+	[BZ #23140]
+	* localedata/locales/ast_ES (mon): Rename to...
+	(alt_mon): This.
+	(mon): Import from CLDR (genitive case).
+
 2018-06-29  Daniel Alvarez  <dalvarez@redhat.com>
 	    Jakub Sitnicki  <jkbs@redhat.com>
 
diff --git a/NEWS b/NEWS
index 9d6fc08eb3..d1de6830a1 100644
--- a/NEWS
+++ b/NEWS
@@ -25,9 +25,9 @@ Major new features:
     fMxdivfNx functions.
 
 * Nominative and genitive month names are now supported for the following
-  languages: Catalan, Czech, Kashubian, Scottish Gaelic, Upper Sorbian,
-  and Walloon.  The following languages now support abbreviated alternative
-  month names: Catalan, Greek, and Kashubian.
+  languages: Asturian, Catalan, Czech, Kashubian, Scottish Gaelic,
+  Upper Sorbian, and Walloon.  The following languages now support
+  abbreviated alternative month names: Catalan, Greek, and Kashubian.
 
 * Building and running on GNU/Hurd systems now works without out-of-tree
   patches.
diff --git a/localedata/locales/ast_ES b/localedata/locales/ast_ES
index ffa46b85b9..488455ae24 100644
--- a/localedata/locales/ast_ES
+++ b/localedata/locales/ast_ES
@@ -96,7 +96,7 @@ abmon   "xin";"feb";/
         "xnt";"ago";/
         "set";"och";/
         "pay";"avi"
-mon     "xineru";/
+alt_mon "xineru";/
         "febreru";/
         "marzu";/
         "abril";/
@@ -111,6 +111,21 @@ mon     "xineru";/
 d_t_fmt "%a %d %b %Y %T %Z"
 d_fmt   "%d//%m//%y"
 t_fmt   "%T"
+% Month names in genitive form:
+% de xineru, de febreru, de marzu, d’abril, de mayu, de xunu,
+% de xunetu, d’agostu, de setiembre, d’ochobre, de payares, d’avientu
+mon     "de xineru";/
+        "de febreru";/
+        "de marzu";/
+        "d<U2019>abril";/
+        "de mayu";/
+        "de xunu";/
+        "de xunetu";/
+        "d<U2019>agostu";/
+        "de setiembre";/
+        "d<U2019>ochobre";/
+        "de payares";/
+        "d<U2019>avientu"
 am_pm   "";""
 t_fmt_ampm ""
 week 7;19971130;4