diff --git a/boards/b-l072z-lrwan1/Makefile.include b/boards/b-l072z-lrwan1/Makefile.include
index 2993d2f1de..8c5857aafc 100644
--- a/boards/b-l072z-lrwan1/Makefile.include
+++ b/boards/b-l072z-lrwan1/Makefile.include
@@ -13,7 +13,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 include $(RIOTMAKE)/tools/serial.inc.mk
 
 # this board has an on-board ST-link adapter
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # call a 'reset halt' command before starting the debugger
 export OPENOCD_DBG_START_CMD = -c 'reset halt'
diff --git a/boards/b-l475e-iot01a/Makefile.include b/boards/b-l475e-iot01a/Makefile.include
index 9949d41e7f..7ab1ad1004 100644
--- a/boards/b-l475e-iot01a/Makefile.include
+++ b/boards/b-l475e-iot01a/Makefile.include
@@ -13,7 +13,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 include $(RIOTMAKE)/tools/serial.inc.mk
 
 # this board has an on-board ST-link adapter
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/cc2538dk/Makefile.include b/boards/cc2538dk/Makefile.include
index 91b36cbcc5..363c58024c 100644
--- a/boards/cc2538dk/Makefile.include
+++ b/boards/cc2538dk/Makefile.include
@@ -3,7 +3,7 @@ export CPU        = cc2538
 export CPU_MODEL ?= cc2538nf53
 
 # the SmartRF06 Evaluation Board serial numbers all begin with "06EB":
-export PROGRAMMER_SERIAL ?= 06EB
+PROGRAMMER_SERIAL ?= 06EB
 
 # setup serial terminal
 # the debug UART is always the second tty with the matching serial number:
diff --git a/boards/common/frdm/Makefile.include b/boards/common/frdm/Makefile.include
index 81a98274f1..1c496ef7bd 100644
--- a/boards/common/frdm/Makefile.include
+++ b/boards/common/frdm/Makefile.include
@@ -4,8 +4,8 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 
 # Use the shared OpenOCD configuration
 # Using dap or jlink depends on which firmware the OpenSDA debugger is running
-export DEBUG_ADAPTER ?= dap
-#export DEBUG_ADAPTER ?= jlink
+DEBUG_ADAPTER ?= dap
+#DEBUG_ADAPTER ?= jlink
 
 # OpenOCD v0.10.0 and newer have built-in support for disabling the Kinetis
 # watchdog automatically. Some older releases of Ubuntu and Debian have only
diff --git a/boards/common/kw41z/Makefile.include b/boards/common/kw41z/Makefile.include
index 3957633b96..cc41cc464d 100644
--- a/boards/common/kw41z/Makefile.include
+++ b/boards/common/kw41z/Makefile.include
@@ -7,7 +7,7 @@ INCLUDES += -I$(RIOTBOARD)/common/kw41z/include
 USEMODULE += boards_common_kw41z
 
 # This board comes with OpenSDA configured for JLink compatibility
-export DEBUG_ADAPTER ?= jlink
+DEBUG_ADAPTER ?= jlink
 
 # Include default FRDM board config
 include $(RIOTBOARD)/common/frdm/Makefile.include
diff --git a/boards/common/nrf52/Makefile.include b/boards/common/nrf52/Makefile.include
index 2df50ef0a3..fab00bf457 100644
--- a/boards/common/nrf52/Makefile.include
+++ b/boards/common/nrf52/Makefile.include
@@ -38,7 +38,7 @@ else ifeq (openocd,$(PROGRAMMER))
     # openocd doesn't work (yet) with softdevice
     $(error Cannot use OpenOCD with nordic_softdevice module)
   endif
-  export DEBUG_ADAPTER ?= jlink
+  DEBUG_ADAPTER ?= jlink
   export OPENOCD_CONFIG := $(RIOTBOARD)/common/nrf52/dist/openocd.cfg
   include $(RIOTMAKE)/tools/openocd.inc.mk
 endif
diff --git a/boards/common/nucleo/Makefile.include b/boards/common/nucleo/Makefile.include
index 63464521dc..34cc7539a8 100644
--- a/boards/common/nucleo/Makefile.include
+++ b/boards/common/nucleo/Makefile.include
@@ -13,7 +13,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 include $(RIOTMAKE)/tools/serial.inc.mk
 
 # all Nucleo boards have an on-board ST-link adapter
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # nucleo boards use openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/common/stm32f103c8/Makefile.include b/boards/common/stm32f103c8/Makefile.include
index 120700b236..087851a95c 100644
--- a/boards/common/stm32f103c8/Makefile.include
+++ b/boards/common/stm32f103c8/Makefile.include
@@ -34,8 +34,8 @@ ifeq ($(PROGRAMMER),dfu-util)
 else
 
   # this board uses openocd by default
-  export DEBUG_ADAPTER ?= stlink
-  export STLINK_VERSION ?= 2
+  DEBUG_ADAPTER ?= stlink
+  STLINK_VERSION ?= 2
 
   # call a 'reset halt' command before starting the debugger
   # it is required as `connect_assert_srst` is set
diff --git a/boards/i-nucleo-lrwan1/Makefile.include b/boards/i-nucleo-lrwan1/Makefile.include
index d43c9c4fa5..6039875503 100644
--- a/boards/i-nucleo-lrwan1/Makefile.include
+++ b/boards/i-nucleo-lrwan1/Makefile.include
@@ -13,7 +13,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 include $(RIOTMAKE)/tools/serial.inc.mk
 
 # to flash this board, use an ST-link adapter
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # call a 'reset halt' command before starting the debugger
 export OPENOCD_DBG_START_CMD = -c 'reset halt'
diff --git a/boards/limifrog-v1/Makefile.include b/boards/limifrog-v1/Makefile.include
index 623dad11cc..c68a2e9fa6 100644
--- a/boards/limifrog-v1/Makefile.include
+++ b/boards/limifrog-v1/Makefile.include
@@ -9,8 +9,8 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
-export DEBUG_ADAPTER ?= stlink
-export STLINK_VERSION ?= 2
+DEBUG_ADAPTER ?= stlink
+STLINK_VERSION ?= 2
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/lsn50/Makefile.include b/boards/lsn50/Makefile.include
index 2b0a64dcea..84e196cb5c 100644
--- a/boards/lsn50/Makefile.include
+++ b/boards/lsn50/Makefile.include
@@ -13,7 +13,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 include $(RIOTMAKE)/tools/serial.inc.mk
 
 # By default, flash this board using an ST-link adapter
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # call a 'reset halt' command before starting the debugger
 export OPENOCD_DBG_START_CMD = -c 'reset halt'
diff --git a/boards/maple-mini/Makefile.include b/boards/maple-mini/Makefile.include
index 0214ae6568..9994096cf0 100644
--- a/boards/maple-mini/Makefile.include
+++ b/boards/maple-mini/Makefile.include
@@ -9,7 +9,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/msbiot/Makefile.include b/boards/msbiot/Makefile.include
index 04b0abcec5..f84deed7c6 100644
--- a/boards/msbiot/Makefile.include
+++ b/boards/msbiot/Makefile.include
@@ -12,8 +12,8 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
-export DEBUG_ADAPTER ?= stlink
-export STLINK_VERSION ?= 2
+DEBUG_ADAPTER ?= stlink
+STLINK_VERSION ?= 2
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/mulle/Makefile.include b/boards/mulle/Makefile.include
index d580e79236..6f0a3c2ee9 100644
--- a/boards/mulle/Makefile.include
+++ b/boards/mulle/Makefile.include
@@ -20,12 +20,12 @@ endif
 export CPU_MODEL
 
 # Default debug adapter choice is to use the Mulle programmer board
-export DEBUG_ADAPTER ?= mulle
+DEBUG_ADAPTER ?= mulle
 # Host OS name
 OS := $(shell uname)
 
 # Fall back to PROGRAMMER_SERIAL for backwards compatibility
-export DEBUG_ADAPTER_ID ?= $(PROGRAMMER_SERIAL)
+DEBUG_ADAPTER_ID ?= $(PROGRAMMER_SERIAL)
 
 ifeq ($(PORT),)
   # try to find tty name by serial number, only works on Linux currently.
diff --git a/boards/pba-d-01-kw2x/Makefile.include b/boards/pba-d-01-kw2x/Makefile.include
index d3bc0c6695..0630575241 100644
--- a/boards/pba-d-01-kw2x/Makefile.include
+++ b/boards/pba-d-01-kw2x/Makefile.include
@@ -20,7 +20,7 @@ export OPENOCD_PRE_VERIFY_CMDS += \
 export OPENOCD_EXTRA_INIT
 export PRE_FLASH_CHECK_SCRIPT = $(RIOTCPU)/$(CPU)/dist/check-fcfield.sh
 
-export DEBUG_ADAPTER ?= dap
+DEBUG_ADAPTER ?= dap
 
 # Add board selector (USB serial) to OpenOCD options if specified.
 # Use /dist/tools/usb-serial/list-ttys.sh to find out serial number.
diff --git a/boards/stm32f0discovery/Makefile.include b/boards/stm32f0discovery/Makefile.include
index d959daf281..d8b7fe9467 100644
--- a/boards/stm32f0discovery/Makefile.include
+++ b/boards/stm32f0discovery/Makefile.include
@@ -9,8 +9,8 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
-export DEBUG_ADAPTER ?= stlink
-export STLINK_VERSION ?= 2
+DEBUG_ADAPTER ?= stlink
+STLINK_VERSION ?= 2
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/stm32f3discovery/Makefile.include b/boards/stm32f3discovery/Makefile.include
index 03adf30a93..36a73aa4f9 100644
--- a/boards/stm32f3discovery/Makefile.include
+++ b/boards/stm32f3discovery/Makefile.include
@@ -9,8 +9,8 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
-export DEBUG_ADAPTER ?= stlink
-export STLINK_VERSION ?= 2
+DEBUG_ADAPTER ?= stlink
+STLINK_VERSION ?= 2
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/stm32f429i-disc1/Makefile.include b/boards/stm32f429i-disc1/Makefile.include
index 7115a58821..8fdb8b1b32 100644
--- a/boards/stm32f429i-disc1/Makefile.include
+++ b/boards/stm32f429i-disc1/Makefile.include
@@ -13,7 +13,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 include $(RIOTMAKE)/tools/serial.inc.mk
 
 # this board has an on-board ST-link adapter
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/stm32f4discovery/Makefile.include b/boards/stm32f4discovery/Makefile.include
index c2f07fe6d3..cafdf1d55f 100644
--- a/boards/stm32f4discovery/Makefile.include
+++ b/boards/stm32f4discovery/Makefile.include
@@ -12,8 +12,8 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
-export DEBUG_ADAPTER ?= stlink
-export STLINK_VERSION ?= 2
+DEBUG_ADAPTER ?= stlink
+STLINK_VERSION ?= 2
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/stm32f769i-disco/Makefile.include b/boards/stm32f769i-disco/Makefile.include
index a33251d632..174a171eff 100644
--- a/boards/stm32f769i-disco/Makefile.include
+++ b/boards/stm32f769i-disco/Makefile.include
@@ -13,7 +13,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 include $(RIOTMAKE)/tools/serial.inc.mk
 
 # this board has an on-board ST-link adapter
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/stm32l476g-disco/Makefile.include b/boards/stm32l476g-disco/Makefile.include
index 5f98bef0cd..773cbd8d08 100644
--- a/boards/stm32l476g-disco/Makefile.include
+++ b/boards/stm32l476g-disco/Makefile.include
@@ -12,7 +12,7 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
-export DEBUG_ADAPTER ?= stlink
+DEBUG_ADAPTER ?= stlink
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/ublox-c030-u201/Makefile.include b/boards/ublox-c030-u201/Makefile.include
index 97675e9e82..964e8d0212 100644
--- a/boards/ublox-c030-u201/Makefile.include
+++ b/boards/ublox-c030-u201/Makefile.include
@@ -9,8 +9,8 @@ PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
-export DEBUG_ADAPTER ?= stlink
-export STLINK_VERSION ?= 2-1
+DEBUG_ADAPTER ?= stlink
+STLINK_VERSION ?= 2-1
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk
diff --git a/boards/yunjia-nrf51822/Makefile.include b/boards/yunjia-nrf51822/Makefile.include
index 637067fab0..591fe6bf57 100644
--- a/boards/yunjia-nrf51822/Makefile.include
+++ b/boards/yunjia-nrf51822/Makefile.include
@@ -9,8 +9,8 @@ PORT_LINUX ?= /dev/ttyUSB0
 PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
 
 # This board uses an ST-Link v2 debug adapter
-export DEBUG_ADAPTER ?= stlink
-export STLINK_VERSION ?= 2
+DEBUG_ADAPTER ?= stlink
+STLINK_VERSION ?= 2
 
 # use openocd to program this board
 PROGRAMMER = openocd
diff --git a/dist/tools/buildsystem_sanity_check/check.sh b/dist/tools/buildsystem_sanity_check/check.sh
index 7704287551..f108fe3214 100755
--- a/dist/tools/buildsystem_sanity_check/check.sh
+++ b/dist/tools/buildsystem_sanity_check/check.sh
@@ -55,6 +55,9 @@ UNEXPORTED_VARIABLES+=('RESET' 'RESETFLAGS')
 UNEXPORTED_VARIABLES+=('DEBUGGER' 'DEBUGGER_FLAGS')
 UNEXPORTED_VARIABLES+=('DEBUGSERVER' 'DEBUGSERVER_FLAGS')
 UNEXPORTED_VARIABLES+=('PREFLASHER' 'PREFFLAGS' 'FLASHDEPS')
+UNEXPORTED_VARIABLES+=('DEBUG_ADAPTER' 'DEBUG_ADAPTER_ID')
+UNEXPORTED_VARIABLES+=('PROGRAMMER_SERIAL')
+UNEXPORTED_VARIABLES+=('STLINK_VERSION')
 
 EXPORTED_VARIABLES_ONLY_IN_VARS=()
 check_not_exporting_variables() {
diff --git a/makefiles/boards/sam0.inc.mk b/makefiles/boards/sam0.inc.mk
index 72e76f3a52..5d4186593c 100644
--- a/makefiles/boards/sam0.inc.mk
+++ b/makefiles/boards/sam0.inc.mk
@@ -2,7 +2,7 @@
 PORT_LINUX ?= /dev/ttyACM0
 PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 # Use DEBUG_ADAPTER_ID to specify the programmer serial number to use:
-# export DEBUG_ADAPTER_ID="ATML..."
+# DEBUG_ADAPTER_ID="ATML..."
 
 # The SERIAL setting is only available for backwards compatibility with older
 # settings.
@@ -13,14 +13,14 @@ ifneq (,$(SERIAL))
     $(error Did not find a device with serial $(SERIAL))
   endif
   PORT_LINUX := $(SERIAL_TTY)
-  export DEBUG_ADAPTER_ID ?= $(SERIAL)
+  DEBUG_ADAPTER_ID ?= $(SERIAL)
 endif
 
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
 # Default for these boards is to use a CMSIS-DAP programmer
-export DEBUG_ADAPTER ?= dap
+DEBUG_ADAPTER ?= dap
 
 # EDBG can only be used with a compatible Atmel programmer
 ifeq ($(DEBUG_ADAPTER),dap)
diff --git a/makefiles/tools/edbg.inc.mk b/makefiles/tools/edbg.inc.mk
index 76f6acca54..31a0964865 100644
--- a/makefiles/tools/edbg.inc.mk
+++ b/makefiles/tools/edbg.inc.mk
@@ -5,7 +5,7 @@ FLASHFILE ?= $(BINFILE)
 # Use USB serial number to select device when more than one is connected
 # Use /dist/tools/usb-serial/list-ttys.sh to find out serial number.
 #   Usage:
-# export DEBUG_ADAPTER_ID="ATML..."
+# DEBUG_ADAPTER_ID="ATML..."
 # BOARD=<board> make flash
 ifneq (,$(DEBUG_ADAPTER_ID))
   EDBG_ARGS += --serial $(DEBUG_ADAPTER_ID)
diff --git a/makefiles/tools/openocd-adapters/mulle.inc.mk b/makefiles/tools/openocd-adapters/mulle.inc.mk
index 3004e09b34..4e1da73428 100644
--- a/makefiles/tools/openocd-adapters/mulle.inc.mk
+++ b/makefiles/tools/openocd-adapters/mulle.inc.mk
@@ -3,7 +3,7 @@
 # programmer board serial number.
 
 # Fall back to PROGRAMMER_SERIAL for backwards compatibility
-export DEBUG_ADAPTER_ID ?= $(PROGRAMMER_SERIAL)
+DEBUG_ADAPTER_ID ?= $(PROGRAMMER_SERIAL)
 
 ifneq (,$(DEBUG_ADAPTER_ID))
   # Makefile-way of comparing numbers, using lexicographical sorting since we