diff --git a/mk/board_avr.mk b/mk/board_avr.mk
index c1fdb3dc28..678be9b3fb 100644
--- a/mk/board_avr.mk
+++ b/mk/board_avr.mk
@@ -7,7 +7,7 @@ include $(MK_DIR)/find_tools.mk
 # Tool options
 #
 DEFINES         =   -DF_CPU=$(F_CPU)
-DEFINES        +=   -DSKETCH=\"$(SKETCH)\"
+DEFINES        +=   -DSKETCH=\"$(SKETCH)\" -DAPM_BUILD_DIRECTORY=APM_BUILD_$(SKETCH)
 DEFINES        +=   $(EXTRAFLAGS) # from user config.mk
 DEFINES        +=   -DCONFIG_HAL_BOARD=$(HAL_BOARD)
 WARNFLAGS       =   -Wformat -Wall -Wshadow -Wpointer-arith -Wcast-align
diff --git a/mk/board_avr_sitl.mk b/mk/board_avr_sitl.mk
index 8e85f64e61..3e4ccb87c4 100644
--- a/mk/board_avr_sitl.mk
+++ b/mk/board_avr_sitl.mk
@@ -6,7 +6,7 @@ include $(MK_DIR)/find_tools.mk
 # Tool options
 #
 DEFINES         =   -DF_CPU=$(F_CPU)
-DEFINES        +=   -DSKETCH=\"$(SKETCH)\" -DSKETCHNAME="\"$(SKETCH)\""
+DEFINES        +=   -DSKETCH=\"$(SKETCH)\" -DSKETCHNAME="\"$(SKETCH)\"" -DAPM_BUILD_DIRECTORY=APM_BUILD_$(SKETCH)
 DEFINES        +=   $(EXTRAFLAGS) # from user config.mk
 DEFINES        +=   -DCONFIG_HAL_BOARD=$(HAL_BOARD)
 WARNFLAGS       =   -Wformat -Wall -Wshadow -Wpointer-arith -Wcast-align
diff --git a/mk/board_flymaple.mk b/mk/board_flymaple.mk
index 24e7b20971..e1c3cd4887 100644
--- a/mk/board_flymaple.mk
+++ b/mk/board_flymaple.mk
@@ -32,7 +32,7 @@ LD_MEM_DIR := sram_64k_flash_512k
 # Tool options
 #
 DEFINES         =   -DF_CPU=$(F_CPU) -DMCU_$(MCU) -DBOARD_$(BOARD) -DERROR_LED_PORT=GPIOA -DERROR_LED_PIN=5 -DVECT_TAB_FLASH 
-DEFINES        +=   -DSKETCH=\"$(SKETCH)\"
+DEFINES        +=   -DSKETCH=\"$(SKETCH)\" -DAPM_BUILD_DIRECTORY=APM_BUILD_$(SKETCH)
 DEFINES        +=   $(EXTRAFLAGS) # from user config.mk
 DEFINES        +=   -DCONFIG_HAL_BOARD=$(HAL_BOARD)
 WARNFLAGS       =   -Wformat -Wall -Wshadow -Wpointer-arith -Wcast-align -Wno-psabi
diff --git a/mk/px4_targets.mk b/mk/px4_targets.mk
index 1e6f29950b..024d99a33e 100644
--- a/mk/px4_targets.mk
+++ b/mk/px4_targets.mk
@@ -36,7 +36,7 @@ EXTRAFLAGS += -DPX4_GIT_VERSION="\"$(PX4_GIT_VERSION)\""
 PX4_V1_CONFIG_FILE=$(MK_DIR)/PX4/config_px4fmu-v1_APM.mk
 PX4_V2_CONFIG_FILE=$(MK_DIR)/PX4/config_px4fmu-v2_APM.mk
 
-SKETCHFLAGS=$(SKETCHLIBINCLUDES) -I$(PWD) -DARDUPILOT_BUILD -DCONFIG_HAL_BOARD=HAL_BOARD_PX4 -DSKETCHNAME="\\\"$(SKETCH)\\\"" -DSKETCH_MAIN=ArduPilot_main
+SKETCHFLAGS=$(SKETCHLIBINCLUDES) -I$(PWD) -DARDUPILOT_BUILD -DCONFIG_HAL_BOARD=HAL_BOARD_PX4 -DSKETCHNAME="\\\"$(SKETCH)\\\"" -DSKETCH_MAIN=ArduPilot_main -DAPM_BUILD_DIRECTORY=APM_BUILD_$(SKETCH)
 
 WARNFLAGS = -Wno-psabi -Wno-packed