diff --git a/procio.cr b/procio.cr
index d958bb3..a1d5fe3 100644
--- a/procio.cr
+++ b/procio.cr
@@ -22,7 +22,7 @@ Dir.entries(dir).each do |entry|
 end
 
 result.each do |comm, (r, w)|
-  if r + w > 0
+  if r > 0 && w > 0
     puts %(procio,comm="#{comm}" read_bytes=#{r},write_bytes=#{w} #{time})
   end
 end