diff --git a/Makefile b/Makefile
index 296e371..181282d 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ INCLUDE_DIRS = -I$(ZSTACK_DIR)
 
 # Compiler settings
 CC = sdcc	# sdcc compiler
-CFLAGS = -mcs51 $(INCLUDE_DIRS)  # add include paths to compiler flags
+CFLAGS = -mmcs51 $(INCLUDE_DIRS)  # add include paths to compiler flags
 
 SRC=$(wildcard *.c)
 HEADERS = main.h zigbee_comm.h sensors/bme280.h sensors/wind_vane.h sensors/rain_gauge.h sensors/anemometer.h config.h include/hal_types.h include/hal_defs.h include/hal_timer.h include/ZComDef.h include/OSAL.h include/i2c.h