--- Makefile.orig	2021-02-17 23:21:59.000000000 -0700
+++ Makefile	2021-03-20 09:42:20.913504000 -0600
@@ -28,6 +28,12 @@
 
 USE_RC_SUBR=	passivedns
 
+OPTIONS_DEFINE=	JANSSON
+
+JANSSON_DESC=	Add option for logs in JSON format.
+JANSSON_CONFIGURE_ENABLE=	json
+JANSSON_LIB_DEPENDS=	libjansson.so:devel/jansson
+
 do-install:
 	${INSTALL_PROGRAM} ${WRKSRC}/src/passivedns \
 		${STAGEDIR}${PREFIX}/bin