diff --git a/config.mk b/config.mk
index ea00093..6df2b6c 100644
--- a/config.mk
+++ b/config.mk
@@ -1,5 +1,8 @@
 ##### ZeroMQ
+# ZMQ_PORT is the port used for all communications
 ZMQ_PORT=5556
+# SUBSCRIBER_ADDR is used by the publisher
+# to contact the subscriber
 SUBSCRIBER_ADDR=localhost
 # ZMQ_TOKEN is used by ZeroMQ to detect
 # messages from publishers. Leave as is if not sure.