diff --git a/test/ruby/test_ast.rb b/test/ruby/test_ast.rb
index 898c4fcc3d..8a58a9e6ba 100644
--- a/test/ruby/test_ast.rb
+++ b/test/ruby/test_ast.rb
@@ -1594,7 +1594,7 @@ dummy
     private
     def ast_parse(src, **options)
       begin
-        verbose_bak, $VERBOSE = $VERBOSE, false
+        verbose_bak, $VERBOSE = $VERBOSE, nil
         RubyVM::AbstractSyntaxTree.parse(src, **options)
       ensure
         $VERBOSE = verbose_bak