diff --git a/cpu/cc2538/vectors.c b/cpu/cc2538/vectors.c
index e722089832..0997fb73d6 100644
--- a/cpu/cc2538/vectors.c
+++ b/cpu/cc2538/vectors.c
@@ -22,9 +22,6 @@
 #include "board.h"
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/cc26x0/vectors.c b/cpu/cc26x0/vectors.c
index 1f0a31549a..ae8b477fd3 100644
--- a/cpu/cc26x0/vectors.c
+++ b/cpu/cc26x0/vectors.c
@@ -21,9 +21,6 @@
 #include "board.h"
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/cortexm_common/include/vectors_cortexm.h b/cpu/cortexm_common/include/vectors_cortexm.h
index 27a30dc935..d0957dc277 100644
--- a/cpu/cortexm_common/include/vectors_cortexm.h
+++ b/cpu/cortexm_common/include/vectors_cortexm.h
@@ -61,8 +61,6 @@ typedef struct {
     isr_t vectors[CPU_NONISR_EXCEPTIONS];   /**< shared Cortex-M vectors */
 } cortexm_base_t;
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
 /**
  * @brief   This function is the default entry point after a system reset
  *
diff --git a/cpu/ezr32wg/vectors.c b/cpu/ezr32wg/vectors.c
index ad1ae23b01..a795b2ddf0 100644
--- a/cpu/ezr32wg/vectors.c
+++ b/cpu/ezr32wg/vectors.c
@@ -21,9 +21,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/kinetis/include/vectors_kinetis.h b/cpu/kinetis/include/vectors_kinetis.h
index 26068d600b..9c7b93a7a7 100644
--- a/cpu/kinetis/include/vectors_kinetis.h
+++ b/cpu/kinetis/include/vectors_kinetis.h
@@ -28,11 +28,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief memory markers as defined in the linker script
- */
-extern uint32_t _estack;
-
 /**
  * @brief Dummy handler
  */
diff --git a/cpu/lm4f120/vectors.c b/cpu/lm4f120/vectors.c
index 5c48f48c48..94ab2ac75e 100644
--- a/cpu/lm4f120/vectors.c
+++ b/cpu/lm4f120/vectors.c
@@ -19,9 +19,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/lpc1768/vectors.c b/cpu/lpc1768/vectors.c
index 18322629ce..f464fac0a7 100644
--- a/cpu/lpc1768/vectors.c
+++ b/cpu/lpc1768/vectors.c
@@ -21,9 +21,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/nrf51/vectors.c b/cpu/nrf51/vectors.c
index 19af0b1ac8..57eeb18c45 100644
--- a/cpu/nrf51/vectors.c
+++ b/cpu/nrf51/vectors.c
@@ -22,9 +22,6 @@
 #include "cpu.h"
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/nrf52/vectors.c b/cpu/nrf52/vectors.c
index e05e3afd38..fcc0d54039 100644
--- a/cpu/nrf52/vectors.c
+++ b/cpu/nrf52/vectors.c
@@ -24,9 +24,6 @@
 #include "cpu.h"
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/sam3/vectors.c b/cpu/sam3/vectors.c
index 90fee53e90..c9dd3c1bb3 100644
--- a/cpu/sam3/vectors.c
+++ b/cpu/sam3/vectors.c
@@ -21,9 +21,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/samd21/vectors.c b/cpu/samd21/vectors.c
index c1da5518a1..945074f97d 100644
--- a/cpu/samd21/vectors.c
+++ b/cpu/samd21/vectors.c
@@ -22,9 +22,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/saml21/vectors.c b/cpu/saml21/vectors.c
index 3f490dc347..8861300d33 100644
--- a/cpu/saml21/vectors.c
+++ b/cpu/saml21/vectors.c
@@ -25,9 +25,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/stm32f3/vectors.c b/cpu/stm32f3/vectors.c
index 98a6ecb7d4..b04bb4b6b2 100644
--- a/cpu/stm32f3/vectors.c
+++ b/cpu/stm32f3/vectors.c
@@ -21,9 +21,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/stm32l1/vectors.c b/cpu/stm32l1/vectors.c
index 7ef508b500..2b33248b34 100644
--- a/cpu/stm32l1/vectors.c
+++ b/cpu/stm32l1/vectors.c
@@ -22,9 +22,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {
diff --git a/cpu/stm32l4/vectors.c b/cpu/stm32l4/vectors.c
index d7e019eb9b..3c06a532b8 100644
--- a/cpu/stm32l4/vectors.c
+++ b/cpu/stm32l4/vectors.c
@@ -21,9 +21,6 @@
 #include <stdint.h>
 #include "vectors_cortexm.h"
 
-/* get the start of the ISR stack as defined in the linkerscript */
-extern uint32_t _estack;
-
 /* define a local dummy handler as it needs to be in the same compilation unit
  * as the alias definition */
 void dummy_handler(void) {