diff --git a/test/ruby/test_settracefunc.rb b/test/ruby/test_settracefunc.rb
index 80490204ca..1515767a57 100644
--- a/test/ruby/test_settracefunc.rb
+++ b/test/ruby/test_settracefunc.rb
@@ -2295,15 +2295,17 @@ class TestSetTraceFunc < Test::Unit::TestCase
 
   def test_tracepoint_opt_invokebuiltin_delegate_leave
     code = 'puts RubyVM::InstructionSequence.of("\x00".method(:unpack)).disasm'
-    out, _err, _status = EnvUtil.invoke_ruby(['-e', code], '', true)
+    out = EnvUtil.invoke_ruby(['-e', code], '', true).first
     assert_match /^0000 opt_invokebuiltin_delegate_leave /, out
 
-    events = []
-    TracePoint.new(:return) do |tp|
-      events << [tp.event, tp.method_id]
-    end.enable do
-      "\x00".unpack("c")
-    end
-    assert_equal [[:return, :unpack]], events
+    event = eval(EnvUtil.invoke_ruby(['-e', <<~'EOS'], '', true).first)
+      set_trace_func(proc {}); set_trace_func(nil) # Is it okay that this is required?
+      TracePoint.new(:return) do |tp|
+        p [tp.event, tp.method_id]
+      end.enable do
+        "\x00".unpack("c")
+      end
+    EOS
+    assert_equal [:return, :unpack], event
   end
 end