diff --git a/spec/cases/count_open_pipes.rb b/spec/cases/count_open_pipes.rb
index 0245602c..e54d333b 100644
--- a/spec/cases/count_open_pipes.rb
+++ b/spec/cases/count_open_pipes.rb
@@ -1,5 +1,5 @@
 require './spec/cases/helper'
-count = ->(*) { `lsof | grep pipe | wc -l`.to_i }
+count = ->(*) { `lsof -l | grep pipe | wc -l`.to_i }
 start = count.()
 results = Parallel.map(Array.new(20), :in_processes => 20, &count)
 puts results.max - start