diff --git a/net/websocket/frames.lua b/net/websocket/frames.lua
index bf61628f7..c22a12de9 100644
--- a/net/websocket/frames.lua
+++ b/net/websocket/frames.lua
@@ -77,7 +77,6 @@ local function parse_frame_header(frame)
 end
 
 -- XORs the string `str` with the array of bytes `key`
--- TODO: optimize
 local function apply_mask(str, key, from, to)
 	return sxor(str:sub(from or 1, to or -1), key);
 end