diff --git a/README.md b/README.md
index ebdb94b..d523919 100644
--- a/README.md
+++ b/README.md
@@ -10,3 +10,4 @@ TODO
 
 ## Usage
 	./proxy <local-address> <local-port> <remote-address> <remote-port>
+### If the program doesn't work, check the errno. Run 'errno $?' to get the resulting error. Also, CHECK YOUR FIREWALL!!!