diff --git a/monitor/Makefile.am b/monitor/Makefile.am
index 9575244..185c2e3 100644
--- a/monitor/Makefile.am
+++ b/monitor/Makefile.am
@@ -11,11 +11,6 @@
 	tach_sensor.cpp \
 	conditions.cpp
 
-nodist_phosphor_fan_monitor_SOURCES = \
-	fan_monitor_defs.cpp
-
-BUILT_SOURCES = fan_monitor_defs.cpp
-
 phosphor_fan_monitor_LDADD = \
 	$(SDBUSPLUS_LIBS) \
 	$(SDEVENTPLUS_LIBS) \
@@ -30,5 +25,13 @@
 	${PHOSPHOR_DBUS_INTERFACES_CFLAGS} \
 	-flto
 
+if WANT_JSON
+phosphor_fan_monitor_SOURCES += json_parser.cpp
+else
+BUILT_SOURCES = fan_monitor_defs.cpp
+nodist_phosphor_fan_monitor_SOURCES = \
+	fan_monitor_defs.cpp
+
 fan_monitor_defs.cpp: ${srcdir}/gen-fan-monitor-defs.py
 	$(AM_V_GEN)$(GEN_FAN_MONITOR_DEFS) > ${builddir}/$@
+endif