diff --git a/Doxyfile b/Doxyfile
index 0cabeb0759..afa2b69504 100644
--- a/Doxyfile
+++ b/Doxyfile
@@ -1528,7 +1528,6 @@ PREDEFINED             = USE_GPS \
                          USE_MAGNETOMETER \
                          USE_BAROMETER \
                          USE_LED \
-                         USE_SYS_TIME \
                          SPI_MASTER \
                          SPI_SLAVE \
                          USE_SPI0 \
diff --git a/conf/airframes/examples/demo.xml b/conf/airframes/examples/demo.xml
index e4578cdb43..d4998a85c6 100644
--- a/conf/airframes/examples/demo.xml
+++ b/conf/airframes/examples/demo.xml
@@ -23,7 +23,7 @@ demo2.ARCHDIR = $(ARCH)
 demo2.CFLAGS += -DBOARD_CONFIG=\"conf_demo.h\"
 demo2.srcs = main_demo2.c
 
-demo2.CFLAGS += -DPERIODIC_FREQUENCY='100.' -DUSE_SYS_TIME
+demo2.CFLAGS += -DPERIODIC_FREQUENCY='100.'
 demo2.srcs += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
 
 demo2.CFLAGS += -DUSE_LED
@@ -36,7 +36,7 @@ demo3.ARCHDIR = $(ARCH)
 demo3.CFLAGS += -DBOARD_CONFIG=\"conf_demo.h\"
 demo3.srcs = main_demo3.c
 
-demo3.CFLAGS += -DPERIODIC_FREQUENCY='10.' -DUSE_SYS_TIME
+demo3.CFLAGS += -DPERIODIC_FREQUENCY='10.'
 demo3.srcs += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
 
 demo3.CFLAGS += -DUSE_LED
@@ -55,7 +55,7 @@ demo4.ARCHDIR = $(ARCH)
 demo4.CFLAGS += -DBOARD_CONFIG=\"conf_demo.h\"
 demo4.srcs = main_demo4.c
 
-demo4.CFLAGS += -DPERIODIC_FREQUENCY='100.' -DUSE_SYS_TIME
+demo4.CFLAGS += -DPERIODIC_FREQUENCY='100.'
 demo4.srcs += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
 
 demo4.CFLAGS += -DUSE_LED
@@ -78,7 +78,7 @@ demo5.ARCHDIR = $(ARCH)
 demo5.CFLAGS += -DBOARD_CONFIG=\"conf_demo.h\"
 demo5.srcs = main_demo5.c
 
-demo5.CFLAGS += -DPERIODIC_FREQUENCY='100.' -DUSE_SYS_TIME
+demo5.CFLAGS += -DPERIODIC_FREQUENCY='100.'
 demo5.srcs += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
 
 demo5.CFLAGS += -DUSE_LED
diff --git a/conf/airframes/wind_tunnel.xml b/conf/airframes/wind_tunnel.xml
index 73849c99d3..1d82b0e1ea 100644
--- a/conf/airframes/wind_tunnel.xml
+++ b/conf/airframes/wind_tunnel.xml
@@ -14,7 +14,7 @@ ap.ARCHDIR = $(ARCH)
 ap.CFLAGS += -DBOARD_CONFIG=\"conf_demo.h\" -I$(WIND_TUNNEL)
 ap.srcs = $(WIND_TUNNEL)/main.c
 
-ap.CFLAGS += -DPERIODIC_FREQUENCY='10.' -DUSE_SYS_TIME
+ap.CFLAGS += -DPERIODIC_FREQUENCY='10.'
 ap.srcs += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
 
 ap.CFLAGS += -DUSE_LED
@@ -44,7 +44,7 @@ mb.ARCHDIR = $(ARCH)
 mb.CFLAGS += -DBOARD_CONFIG=\"conf_demo.h\" -I$(WIND_TUNNEL) -I$(MB)
 mb.srcs = $(WIND_TUNNEL)/main_mb.c
 
-mb.CFLAGS += -DPERIODIC_FREQUENCY='100.' -DUSE_SYS_TIME
+mb.CFLAGS += -DPERIODIC_FREQUENCY='100.'
 mb.srcs += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
 
 mb.CFLAGS += -DUSE_LED
diff --git a/conf/firmwares/rotorcraft.makefile b/conf/firmwares/rotorcraft.makefile
index 28a0a62bc9..d178b39364 100644
--- a/conf/firmwares/rotorcraft.makefile
+++ b/conf/firmwares/rotorcraft.makefile
@@ -55,7 +55,6 @@ $(TARGET).CFLAGS += -DPERIODIC_FREQUENCY=$(PERIODIC_FREQUENCY)
 #
 # Systime
 #
-$(TARGET).CFLAGS += -DUSE_SYS_TIME
 $(TARGET).srcs += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
 
 
diff --git a/conf/firmwares/setup.makefile b/conf/firmwares/setup.makefile
index cb0827e31f..4284507190 100644
--- a/conf/firmwares/setup.makefile
+++ b/conf/firmwares/setup.makefile
@@ -27,7 +27,6 @@ ifneq ($(SYS_TIME_LED),none)
 tunnel.CFLAGS += -DSYS_TIME_LED=$(SYS_TIME_LED)
 endif
 tunnel.CFLAGS += -DPERIODIC_FREQUENCY='512.'
-tunnel.CFLAGS += -DUSE_SYS_TIME
 tunnel.srcs   += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
 endif
 
@@ -75,7 +74,6 @@ endif
 setup_actuators.CFLAGS += -DUSE_LED -DPERIPHERALS_AUTO_INIT
 setup_actuators.srcs   += mcu.c $(SRC_ARCH)/mcu_arch.c
 
-setup_actuators.CFLAGS += -DUSE_SYS_TIME
 ifneq ($(SYS_TIME_LED),none)
 setup_actuators.CFLAGS += -DSYS_TIME_LED=$(SYS_TIME_LED)
 endif
diff --git a/conf/firmwares/subsystems/fixedwing/autopilot.makefile b/conf/firmwares/subsystems/fixedwing/autopilot.makefile
index 6dfc581ea8..9defff09be 100644
--- a/conf/firmwares/subsystems/fixedwing/autopilot.makefile
+++ b/conf/firmwares/subsystems/fixedwing/autopilot.makefile
@@ -58,7 +58,6 @@ PERIODIC_FREQUENCY ?= 60
 $(TARGET).CFLAGS += -DPERIODIC_FREQUENCY=$(PERIODIC_FREQUENCY)
 
 $(TARGET).srcs   += mcu_periph/sys_time.c $(SRC_ARCH)/mcu_periph/sys_time_arch.c
-$(TARGET).CFLAGS += -DUSE_SYS_TIME
 
 #
 # InterMCU & Commands
diff --git a/conf/firmwares/test_progs.makefile b/conf/firmwares/test_progs.makefile
index 1299e96074..091e58752c 100644
--- a/conf/firmwares/test_progs.makefile
+++ b/conf/firmwares/test_progs.makefile
@@ -49,7 +49,6 @@ PERIODIC_FREQUENCY ?= 512
 COMMON_TEST_CFLAGS  = -I$(SRC_BOARD) -DBOARD_CONFIG=$(BOARD_CFG)
 COMMON_TEST_CFLAGS += -DPERIPHERALS_AUTO_INIT
 COMMON_TEST_SRCS    = mcu.c $(SRC_ARCH)/mcu_arch.c
-COMMON_TEST_CFLAGS += -DUSE_SYS_TIME
 ifneq ($(SYS_TIME_LED),none)
   COMMON_TEST_CFLAGS += -DSYS_TIME_LED=$(SYS_TIME_LED)
 endif