diff --git a/site.mk b/site.mk
index 23e55a4..3631488 100755
--- a/site.mk
+++ b/site.mk
@@ -31,7 +31,7 @@ GLUON_SITE_PACKAGES := \
 	firewall \
 	haveged
 
-# Allow overriding the these variables from the command line
+# Variables set with ?= can be overwritten from the command line
 GLUON_RELEASE ?= $(patsubst v%,%,$(shell git -C $(GLUON_SITEDIR) describe --tags --dirty=+))
 export GLUON_BRANCH ?= stable
 GLUON_PRIORITY ?= 0