diff --git a/Makefile b/Makefile
index 4d06148..c9ac771 100644
--- a/Makefile
+++ b/Makefile
@@ -123,7 +123,7 @@ CSRC = $(STARTUPSRC) \
        $(BOARDSRC) \
        $(STREAMSSRC) \
        usbcfg.c \
-       main.c si5351.c tlv320aic3204.c dsp.c plot.c ui.c ili9341.c numfont20x22.c Font5x7.c flash.c adc.c
+       main.c si5351.c tlv320aic3204.c dsp.c plot.c ui.c ili9341.c numfont20x22.c Font5x7.c flash.c adc.c rtc.c
 
 # C++ sources that can be compiled in ARM or THUMB mode depending on the global
 # setting.
@@ -205,9 +205,11 @@ CPPWARN = -Wall -Wextra -Wundef
 
 # List all user C define here, like -D_DEBUG=1
 UDEFS = -DSHELL_CMD_TEST_ENABLED=FALSE -DSHELL_CMD_MEM_ENABLED=FALSE -DARM_MATH_CM0 -DVERSION=\"$(VERSION)\"
+#Enable if install external 32.768kHz clock quartz on PC14 and PC15 pins on STM32 CPU
+#UDEFS+= -DVNA_USE_LSE
 
 # Define ASM defines here
-UADEFS =
+UADEFS = 
 
 # List all user directories here
 UINCDIR =