diff --git a/vlib/v/gen/fn.v b/vlib/v/gen/fn.v
index c3abc77f11..93e4a04a03 100644
--- a/vlib/v/gen/fn.v
+++ b/vlib/v/gen/fn.v
@@ -270,7 +270,7 @@ fn (mut g Gen) call_expr(node ast.CallExpr) {
 		g.write('$styp $tmp_opt = ')
 	}
 	if node.is_method && !node.is_field {
-		if node.name == 'writeln' && g.pref.show_cc &&
+		if node.name == 'writeln' && g.pref.experimental &&
 			node.args.len > 0 && node.args[0].expr is ast.StringInterLiteral &&
 			g.table.get_type_symbol(node.receiver_type).name == 'strings.Builder' {
 			g.string_inter_literal_sb_optimized(node)
@@ -644,7 +644,7 @@ fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type table.Type) {
 			}
 		}
 		if !g.is_json_fn {
-			arg_typ_sym := g.table.get_type_symbol(arg.typ)            
+			arg_typ_sym := g.table.get_type_symbol(arg.typ)
 			if arg_typ_sym.kind != .function {
 				g.write('(voidptr)&/*qq*/')
 			}
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index 0e4ea9aa47..39c57bd96c 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -116,6 +116,7 @@ pub mut:
 	error_limit         int
 	is_vweb             bool // skip _ var warning in templates
 	only_check_syntax   bool // when true, just parse the files, then stop, before running checker
+	experimental        bool // enable experimental features
 }
 
 pub fn parse_args(args []string) (&Preferences, string) {
@@ -196,6 +197,9 @@ pub fn parse_args(args []string) (&Preferences, string) {
 			'-showcc' {
 				res.show_cc = true
 			}
+			'-experimental' {
+				res.experimental = true
+			}
 			'-usecache' {
 				res.use_cache = true
 			}