diff --git a/test/plugin/test_in_tail.rb b/test/plugin/test_in_tail.rb
index e23f764974..9bef349c65 100644
--- a/test/plugin/test_in_tail.rb
+++ b/test/plugin/test_in_tail.rb
@@ -401,7 +401,7 @@ def test_lf
 
     d = create_driver
 
-    d.run do
+    d.run(expect_emits: 1) do
       File.open("#{TMP_DIR}/tail.txt", "ab") {|f|
         f.print "test3"
       }
@@ -410,7 +410,6 @@ def test_lf
       File.open("#{TMP_DIR}/tail.txt", "ab") {|f|
         f.puts "test4"
       }
-      sleep 1
     end
 
     events = d.events