diff --git a/procio.cr b/procio.cr
index 54ce48b..d958bb3 100644
--- a/procio.cr
+++ b/procio.cr
@@ -1,9 +1,9 @@
-dir = ENV.fetch("PROCIO_DIR", "/proc")
+dir = Path[ENV.fetch("PROCIO_DIR", "/proc")]
 result = {} of String => Array(UInt64)
 time = Time.local.to_s("%s%9N")
 
 Dir.entries(dir).each do |entry|
-  entry =~ /^\d+$/ || next 
+  next unless (entry =~ /^\d+$/) && File.directory?(dir/entry)
 
   begin
     comm = File.read("#{dir}/#{entry}/comm").chomp