https://code.google.com/p/clementine-player/source/detail?r=5e685b2b1425
https://bugs.gentoo.org/show_bug.cgi?id=420871

--- src/CMakeLists.txt
+++ src/CMakeLists.txt
@@ -634,7 +634,7 @@
   if (NOT LINGUAS OR LINGUAS STREQUAL "None")
     set (LANGUAGES "")
   else (NOT LINGUAS OR LINGUAS STREQUAL "None")
-    string(REGEX MATCHALL [a-zA-Z_]+
+    string(REGEX MATCHALL [a-zA-Z_@]+
            LANGUAGES ${LINGUAS})
   endif (NOT LINGUAS OR LINGUAS STREQUAL "None")
 endif (LINGUAS STREQUAL "All")