diff --git a/cfg/help.mk b/cfg/help.mk
index 830eb3b..ea8f18b 100644
--- a/cfg/help.mk
+++ b/cfg/help.mk
@@ -8,6 +8,7 @@ help:
 	@echo "  help:    This help"
 	@echo
 	@echo "-- Variables --"
+	@echo "  DISABLE_AV:   Set to \"1\" to force building without audio call support"
 	@echo "  USER_CFLAGS:  Add custom flags to default CFLAGS"
 	@echo "  USER_LDFLAGS: Add custom flags to default LDFLAGS"
 	@echo "  PREFIX:       Specify a prefix directory for binaries, data files,... (default is \"$(abspath $(PREFIX))\")"