diff --git a/test/plugin/test_in_tail.rb b/test/plugin/test_in_tail.rb
index 4449e29a47..90e466a1db 100644
--- a/test/plugin/test_in_tail.rb
+++ b/test/plugin/test_in_tail.rb
@@ -985,6 +985,7 @@ def sub_test_rotate_file(config = nil, expect_emits: nil, expect_records: nil, t
 
       d = create_driver(config)
       d.run(expect_emits: expect_emits, expect_records: expect_records, timeout: timeout) do
+        sleep(0.1) while d.instance.instance_variable_get(:@startup)
         size = d.emit_count
         file.puts "test3"
         file.puts "test4"