diff --git a/S05-substitution/subst.t b/S05-substitution/subst.t
index e695f1512c..f586b56805 100644
--- a/S05-substitution/subst.t
+++ b/S05-substitution/subst.t
@@ -1,8 +1,9 @@
 use v6;
-
+use lib 't/spec/packages';
 use Test;
+use Test::Util;
 
-plan 179;
+plan 180;
 
 # L<S05/Substitution/>
 
@@ -568,4 +569,11 @@ is '12'.subst(/(.)(.)/,{$()*2}),'24', '.. and do nifty things in closures';
     is S:g[(o)] = $0.uc, "fOO", "non-mutating global substitution assignment works ($0)";
 }
 
+# RT #128809
+{
+    is_run 'await ^30 .map: { start { S/.+/{$/.chars.print}/ given "abc"; } }', {
+        :err(''), :out('3' x 30)
+    }, 'code in replacement part of s/// has correct scoping';
+}
+
 # vim: ft=perl6