diff --git a/port/ez430-rf2560/Makefile b/port/ez430-rf2560/Makefile
index 8a086ac90..bc4d94c1a 100644
--- a/port/ez430-rf2560/Makefile
+++ b/port/ez430-rf2560/Makefile
@@ -8,7 +8,7 @@ CC2560B = bluetooth_init_cc2560B_1.6_BT_Spec_4.1.o
 CC2564B = bluetooth_init_cc2564B_1.6_BT_Spec_4.1.o
 CC2567  = CC256x_BT_Service_Pack_2.8_ANT_1.16.o
 
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 VPATH += example
 VPATH += firmware
 VPATH += src
diff --git a/port/libusb-intel/Makefile b/port/libusb-intel/Makefile
index f331f44aa..ba253ca10 100644
--- a/port/libusb-intel/Makefile
+++ b/port/libusb-intel/Makefile
@@ -1,5 +1,5 @@
 # Makefile for libusb based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += main.c btstack_stdin_posix.c btstack_tlv_posix.c
 
diff --git a/port/libusb/Makefile b/port/libusb/Makefile
index 943a1a8f9..e71ca1a24 100644
--- a/port/libusb/Makefile
+++ b/port/libusb/Makefile
@@ -1,5 +1,5 @@
 # Makefile for libusb based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += main.c btstack_stdin_posix.c btstack_tlv_posix.c
 
diff --git a/port/max32630-fthr/example/template/Makefile b/port/max32630-fthr/example/template/Makefile
index 953c0385c..d0aa04529 100644
--- a/port/max32630-fthr/example/template/Makefile
+++ b/port/max32630-fthr/example/template/Makefile
@@ -93,7 +93,7 @@ VPATH += $(BOARD_DIR)/Source
 IPATH += $(BOARD_DIR)/Include
 
 # BTstack
-BTSTACK_ROOT = ../../../..
+BTSTACK_ROOT ?= ../../../..
 VPATH += $(BTSTACK_ROOT)/chipset/cc256x
 VPATH += $(BTSTACK_ROOT)/example
 VPATH += $(BTSTACK_ROOT)/port/pegasus-max3263x
diff --git a/port/msp-exp430f5438-cc2564b/Makefile b/port/msp-exp430f5438-cc2564b/Makefile
index 5d0866e74..0c18d0084 100644
--- a/port/msp-exp430f5438-cc2564b/Makefile
+++ b/port/msp-exp430f5438-cc2564b/Makefile
@@ -8,7 +8,7 @@ CC2560B = bluetooth_init_cc2560B_1.6_BT_Spec_4.1.o
 CC2564B = bluetooth_init_cc2564B_1.6_BT_Spec_4.1.o
 CC2567  = CC256x_BT_Service_Pack_2.8_ANT_1.16.o
 
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 VPATH += example
 VPATH += firmware
 VPATH += src
diff --git a/port/msp430f5229lp-cc2564b/Makefile b/port/msp430f5229lp-cc2564b/Makefile
index e6c9b4dff..89c9883f2 100644
--- a/port/msp430f5229lp-cc2564b/Makefile
+++ b/port/msp430f5229lp-cc2564b/Makefile
@@ -8,7 +8,7 @@ CC2560B = bluetooth_init_cc2560B_1.6_BT_Spec_4.1.o
 CC2564B = bluetooth_init_cc2564B_1.6_BT_Spec_4.1.o
 CC2567  = CC256x_BT_Service_Pack_2.8_ANT_1.16.o
 
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 VPATH += example
 VPATH += firmware
 VPATH += src
diff --git a/port/mtk/Makefile b/port/mtk/Makefile
index 63fa5a414..9e3a728b3 100644
--- a/port/mtk/Makefile
+++ b/port/mtk/Makefile
@@ -8,7 +8,7 @@ STRIP = $(TOOLCHAIN)/bin/arm-linux-androideabi-strip
 CFLAGS = -march=armv7-a -mfloat-abi=softfp -I$(SYSROOT)/usr/include -fpie -fpic -fPIE -pie#
 LDFLAGS = -Wl,--fix-cortex-a8 -L$(SYSROOT)/usr/lib -fpie -fpic -fPIE -pie
 
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CFLAGS += -I$(BTSTACK_ROOT)/include
 CFLAGS += -I$(BTSTACK_ROOT)/src/
diff --git a/port/nrf5x/pca10028/armgcc/Makefile b/port/nrf5x/pca10028/armgcc/Makefile
index 6de5a875c..8cfd1facd 100755
--- a/port/nrf5x/pca10028/armgcc/Makefile
+++ b/port/nrf5x/pca10028/armgcc/Makefile
@@ -69,7 +69,7 @@ INC_PATHS += -I$(abspath ../../../../../components/libraries/fifo)
 INC_PATHS += -I$(abspath ../../../../../components/toolchain/gcc)
 
 # BTstack territory
-BTSTACK_ROOT = ../../../../../components/btstack
+BTSTACK_ROOT ?= ../../../../../components/btstack
 C_SOURCE_FILES +=   $(abspath $(BTSTACK_ROOT)/port/nrf5x/main.c)
 C_SOURCE_FILES +=   $(abspath $(BTSTACK_ROOT)/port/retarget_blocking.c)
 C_SOURCE_FILES +=   $(abspath $(BTSTACK_ROOT)/platform/embedded/btstack_run_loop_embedded.c)
@@ -216,4 +216,4 @@ flash: $(MAKECMDGOALS)
 	nrfjprog --program $(OUTPUT_BINARY_DIRECTORY)/$<.hex -f nrf51  --chiperase
 	nrfjprog --reset
 
-## Flash softdevice
\ No newline at end of file
+## Flash softdevice
diff --git a/port/posix-h4-atwilc3000/Makefile b/port/posix-h4-atwilc3000/Makefile
index 15a30adcf..a650e8bea 100644
--- a/port/posix-h4-atwilc3000/Makefile
+++ b/port/posix-h4-atwilc3000/Makefile
@@ -1,5 +1,5 @@
 # Makefile for libusb based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += \
 	btstack_chipset_atwilc3000.c \
diff --git a/port/posix-h4-da14581/Makefile b/port/posix-h4-da14581/Makefile
index fb3e4b7c6..fb1ce74ba 100644
--- a/port/posix-h4-da14581/Makefile
+++ b/port/posix-h4-da14581/Makefile
@@ -1,5 +1,5 @@
 # Makefile for libusb based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += \
 	btstack_chipset_da14581.c \
diff --git a/port/posix-h4-da14585/Makefile b/port/posix-h4-da14585/Makefile
index 8f898638f..912f9ddd7 100644
--- a/port/posix-h4-da14585/Makefile
+++ b/port/posix-h4-da14585/Makefile
@@ -1,5 +1,5 @@
 # Makefile for libusb based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += \
 	btstack_chipset_da14581.c \
diff --git a/port/posix-h4-zephyr/Makefile b/port/posix-h4-zephyr/Makefile
index da3195a49..3ae80dcf7 100644
--- a/port/posix-h4-zephyr/Makefile
+++ b/port/posix-h4-zephyr/Makefile
@@ -1,5 +1,5 @@
 # Makefile for posix-h4 based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += \
 	btstack_link_key_db_fs.c \
diff --git a/port/posix-h4/Makefile b/port/posix-h4/Makefile
index 022ea1e92..228251d45 100644
--- a/port/posix-h4/Makefile
+++ b/port/posix-h4/Makefile
@@ -1,5 +1,5 @@
 # Makefile for libusb based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += \
 	bluetooth_init_cc2564B_1.6_BT_Spec_4.1.c \
diff --git a/port/posix-h5-bcm/Makefile b/port/posix-h5-bcm/Makefile
index 3bb2befbd..02ad5840e 100644
--- a/port/posix-h5-bcm/Makefile
+++ b/port/posix-h5-bcm/Makefile
@@ -1,5 +1,5 @@
 # Makefile for libusb based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += \
 	btstack_chipset_bcm.c \
diff --git a/port/posix-h5/Makefile b/port/posix-h5/Makefile
index e64e0252f..11b90e89a 100644
--- a/port/posix-h5/Makefile
+++ b/port/posix-h5/Makefile
@@ -1,5 +1,5 @@
 # Makefile for libusb based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += \
 	bluetooth_init_cc2564B_1.6_BT_Spec_4.1.c \
diff --git a/port/raspi/Makefile b/port/raspi/Makefile
index 313ce01ed..8383d1796 100644
--- a/port/raspi/Makefile
+++ b/port/raspi/Makefile
@@ -1,5 +1,5 @@
 # Makefile for Raspberry Pi
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += \
 	btstack_chipset_bcm.c \
diff --git a/port/stm32-f103rb-nucleo/Makefile b/port/stm32-f103rb-nucleo/Makefile
index 8dda7952e..53ce56119 100644
--- a/port/stm32-f103rb-nucleo/Makefile
+++ b/port/stm32-f103rb-nucleo/Makefile
@@ -7,7 +7,7 @@ BINARY=spp_and_le_counter
 OPENCM3_DIR = libopencm3
 LDSCRIPT = stm32f1-nucleo.ld
 
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 VPATH  = $(BTSTACK_ROOT)/example
 VPATH += $(BTSTACK_ROOT)/src
 VPATH += $(BTSTACK_ROOT)/src/ble
diff --git a/port/stm32-f4discovery-cc256x/Makefile b/port/stm32-f4discovery-cc256x/Makefile
index 926cd54c3..b146f0d61 100644
--- a/port/stm32-f4discovery-cc256x/Makefile
+++ b/port/stm32-f4discovery-cc256x/Makefile
@@ -31,7 +31,7 @@ OPT = -Os
 # Build path
 BUILD_DIR = build
 
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 VPATH += ${BTSTACK_ROOT}/example
 
 ######################################
diff --git a/port/stm32-l073rz-nucleo-em9304/Makefile b/port/stm32-l073rz-nucleo-em9304/Makefile
index e64288fe5..163dabe32 100644
--- a/port/stm32-l073rz-nucleo-em9304/Makefile
+++ b/port/stm32-l073rz-nucleo-em9304/Makefile
@@ -31,7 +31,7 @@ OPT = -Os
 # Build path
 BUILD_DIR = build
 
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 VPATH += ${BTSTACK_ROOT}/example
 
 ######################################
diff --git a/port/windows-h4-zephyr/Makefile b/port/windows-h4-zephyr/Makefile
index 718f777cf..7bd8461fd 100644
--- a/port/windows-h4-zephyr/Makefile
+++ b/port/windows-h4-zephyr/Makefile
@@ -1,5 +1,5 @@
 # Makefile for windows-h4 examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += main.c btstack_stdin_windows.c
 
diff --git a/port/windows-h4/Makefile b/port/windows-h4/Makefile
index 0229a5505..a88b9d2cc 100644
--- a/port/windows-h4/Makefile
+++ b/port/windows-h4/Makefile
@@ -1,5 +1,5 @@
 # Makefile for windows-h4 examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += main.c btstack_stdin_windows.c
 
diff --git a/port/windows-winusb-intel/Makefile b/port/windows-winusb-intel/Makefile
index 58e3adbc6..e24275322 100644
--- a/port/windows-winusb-intel/Makefile
+++ b/port/windows-winusb-intel/Makefile
@@ -1,5 +1,5 @@
 # Makefile for windows WinUSB based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += main.c btstack_stdin_windows.c
 
diff --git a/port/windows-winusb/Makefile b/port/windows-winusb/Makefile
index 7ccf07c0c..598800466 100644
--- a/port/windows-winusb/Makefile
+++ b/port/windows-winusb/Makefile
@@ -1,5 +1,5 @@
 # Makefile for windows WinUSB based examples
-BTSTACK_ROOT = ../..
+BTSTACK_ROOT ?= ../..
 
 CORE += main.c btstack_stdin_windows.c