diff --git a/src/operators.lua b/src/operators.lua
index f1cb3cd..6d96041 100644
--- a/src/operators.lua
+++ b/src/operators.lua
@@ -1,3 +1,6 @@
+--[[    All source files have to be preprocessed before loading.
+	This allows implementing custom operators like bitwise ones.	]]
+
 local fmt = string.format
 local var = "[%w%.%[%]\"\'_]"