diff --git a/utils/antlr/README.md b/utils/antlr/README.md
index 50bf34ab432..7d2112e46bf 100644
--- a/utils/antlr/README.md
+++ b/utils/antlr/README.md
@@ -1,3 +1,7 @@
+## This parser is unsupported
+
+We keep it in this repository for your curiosity. But this is not the parser of ClickHouse.
+
 ## How to generate source code files from grammar
 
 Grammar is located inside `ClickHouseLexer.g4` and `ClickHouseParser.g4` files.