diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index 679bd2702a..770d0b863e 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -1334,7 +1334,7 @@ class TestHash < Test::Unit::TestCase
   def assert_hash_random(obj, dump = obj.inspect)
     a = [obj.hash.to_s]
     3.times {
-      assert_in_out_err(["-e", "print #{dump}.hash"], "") do |r, e|
+      assert_in_out_err(["-e", "print (#{dump}).hash"], "") do |r, e|
         a += r
         assert_equal([], e)
       end