diff --git a/src/box/lua/schema.lua b/src/box/lua/schema.lua
index aba439ffbb5d5e00595ab5da9821fe9fbe6f0d98..774200191c5564abf8024b85dc5781b08c1234be 100644
--- a/src/box/lua/schema.lua
+++ b/src/box/lua/schema.lua
@@ -17,8 +17,8 @@ end
 local builtin = ffi.C
 
 -- performance fixup for hot functions
-local tuple_encode = box.tuple.encode
-local tuple_bless = box.tuple.bless
+local tuple_encode = box.internal.tuple.encode
+local tuple_bless = box.internal.tuple.bless
 local is_tuple = box.tuple.is
 assert(tuple_encode ~= nil and tuple_bless ~= nil and is_tuple ~= nil)
 
diff --git a/src/box/lua/tuple.lua b/src/box/lua/tuple.lua
index a25a28987866d8823d2d989d1dc893dd50445589..eb3946a0f5c5b56372d0157b349297d155666e8d 100644
--- a/src/box/lua/tuple.lua
+++ b/src/box/lua/tuple.lua
@@ -342,7 +342,17 @@ ffi.metatype(tuple_iterator_t, {
     __tostring = function(it) return "<tuple iterator>" end;
 })
 
+-- Free methods, which are not needed anymore.
+internal.tuple.slice = nil
+internal.tuple.transform = nil
+internal.tuple.tuple_to_map = nil
+internal.tuple.tostring = nil
+
 -- internal api for box.select and iterators
-box.tuple.bless = tuple_bless
-box.tuple.encode = tuple_encode
+internal.tuple.bless = tuple_bless
+internal.tuple.encode = tuple_encode
+
+-- The function is internal in a sense that it is not documented.
+-- But it is safe and widely used in the tests. Keep it here at
+-- least for test code.
 box.tuple.is = is_tuple