diff --git a/runtest b/runtest
index e8048502..a4ae259c 100755
--- a/runtest
+++ b/runtest
@@ -4,6 +4,7 @@
 DOWNLOADREPOS_AS_LIB=1
 . ./downloadrepos
 
+# CONFIG_PARAMETERS_SCRIPT_URL can override DEFAULT_PRODUCTION_HOST.
 DEFAULT_PRODUCTION_HOST="${DEFAULT_PRODUCTION_HOST:=pavics.ouranos.ca}"
 
 NOTEBOOKS="$1"