diff --git a/ChangeLog b/ChangeLog
index 8e2e1f4bf..900d7ce0b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2008-08-14  Jean-Sébastien Pédron  <js.pedron@meetic-corp.com>
+
+	* translate.erl (ascii_tolower): Accept 'undefined' as a language and
+	treat it as the empty string.
+
 2008-08-06  Jean-Sébastien Pédron  <js.pedron@meetic-corp.com>
 
 	* src/mod_offline.erl, src/mod_offline_odbc.erl, src/mod_echo.erl,
diff --git a/src/translate.erl b/src/translate.erl
index bc0af1399..bc1d9e0c9 100644
--- a/src/translate.erl
+++ b/src/translate.erl
@@ -159,5 +159,6 @@ ascii_tolower([C | Cs]) when C >= $A, C =< $Z ->
 ascii_tolower([C | Cs]) ->
     [C | ascii_tolower(Cs)];
 ascii_tolower([]) ->
+    [];
+ascii_tolower(undefined) ->
     [].
-