diff --git a/po/ja.po b/po/ja.po
index 4c2f2330b..08403a07a 100644
--- a/po/ja.po
+++ b/po/ja.po
@@ -1366,7 +1366,7 @@ msgstr "11 月"
 #. l10n: Short month name
 #: js/messages.php:183 libraries/common.lib.php:1590
 msgid "Dec"
-msgstr ""
+msgstr "12 月"
 
 #: js/messages.php:186
 #, fuzzy