Index: test/std/re/re.traits/translate_nocase.pass.cpp
===================================================================
--- test/std/re/re.traits/translate_nocase.pass.cpp
+++ test/std/re/re.traits/translate_nocase.pass.cpp
@@ -19,9 +19,6 @@
 // XFAIL: with_system_cxx_lib=macosx10.7
 // XFAIL: with_system_cxx_lib=macosx10.8
 
-// TODO: investigation needed
-// XFAIL: linux-gnu
-
 #include <regex>
 #include <cassert>
 
@@ -47,7 +44,9 @@
         assert(t.translate_nocase('.') == '.');
         assert(t.translate_nocase('a') == 'a');
         assert(t.translate_nocase('1') == '1');
-        assert(t.translate_nocase('\xDA') == '\xFA');
+        // \xDA is initial char of MBS in UTF-8
+        assert(t.translate_nocase('\xDA') == '\xDA');
+        // \xFA is invalid as initial char in UTF-8
         assert(t.translate_nocase('\xFA') == '\xFA');
     }
     {