diff --git a/src/lib/lstrlib.c b/src/lib/lstrlib.c
index 66e4368..4850157 100644
--- a/src/lib/lstrlib.c
+++ b/src/lib/lstrlib.c
@@ -743,6 +743,12 @@ static int str_format (lua_State *L) {
 }
 
 
+static int str_lualex (lua_State *L) {
+  // TODO: Implement
+  return 1;
+}
+
+
 static const luaL_reg strlib[] = {
   {"len", str_len},
   {"sub", str_sub},
@@ -756,6 +762,7 @@ static const luaL_reg strlib[] = {
   {"find", str_find},
   {"gfind", gfind},
   {"gsub", str_gsub},
+  {"lualex", str_lualex},
   {NULL, NULL}
 };
 
diff --git a/test/faf.lua b/test/faf.lua
index 7a09f21..8c226d8 100644
--- a/test/faf.lua
+++ b/test/faf.lua
@@ -120,6 +120,8 @@ assert(str:sub(2) == "bcdefghijklmnop")
 assert(str:sub(2, -2) == "bcdefghijklmno")
 assert(str:sub(2, 8) == "bcdefgh")
 
+assert(str:lualex() == str)
+
 local string_func_names = {}
 local n=0
 
@@ -129,6 +131,7 @@ for k in string do
 end
 assert(table.concat(string_func_names) == table.concat({
   "sub",
+  "lualex",
   "gfind",
   "rep",
   "gsub",