diff --git a/math/units/Makefile b/math/units/Makefile
index 1473bd85f997..028c0bfe30c7 100644
--- a/math/units/Makefile
+++ b/math/units/Makefile
@@ -18,8 +18,8 @@ CONFIGURE_ARGS=	--program-prefix=g
 
 INFO=		units
 
-OPTIONS_DEFAULT=	READLINE
 OPTIONS_DEFINE=		READLINE
+OPTIONS_DEFAULT=	READLINE
 READLINE_USES=	readline:port
 
 post-patch: