diff --git a/opalang/js_syntax/opa_lexer.trx b/opalang/js_syntax/opa_lexer.trx
index 287c2419..cf3074d2 100644
--- a/opalang/js_syntax/opa_lexer.trx
+++ b/opalang/js_syntax/opa_lexer.trx
@@ -240,6 +240,7 @@ keyword <- (
   / "with"
   / "css"
   / "server" / "client" / "exposed" / "protected"
+  / "_"
 )
 
 (* Keywords : Bindings *)