diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index dc99a8c463..30984bc26a 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -3551,7 +3551,7 @@ def test_write_no_garbage
   end
 
   def test_select_leak
-    assert_no_memory_leak([], <<-"end;", <<-"end;", rss: true, timeout: 60)
+    assert_no_memory_leak([], <<-"end;", <<-"end;", rss: true, timeout: 240)
       r, w = IO.pipe
       rset = [r]
       wset = [w]
@@ -3562,6 +3562,7 @@ def test_select_leak
         Thread.pass until th.stop?
         th.kill
         th.join
+        GC.start
       end
     end;
   end
-- 
2.17.1