diff --git a/boards/qemu-i386/include/cpu_conf.h b/boards/qemu-i386/include/cpu_conf.h
index e4c0f59db..638322693 100644
--- a/boards/qemu-i386/include/cpu_conf.h
+++ b/boards/qemu-i386/include/cpu_conf.h
@@ -30,7 +30,6 @@ extern "C" {
 #define THREAD_EXTRA_STACKSIZE_PRINTF            (8192)
 #define THREAD_EXTRA_STACKSIZE_PRINTF_FLOAT      (8192)
 #define THREAD_STACKSIZE_MINIMUM                 (8192)
-#define ISR_STACKSIZE                            (0)
 
 #ifdef __cplusplus
 }
diff --git a/cpu/arm7_common/arm_cpu.c b/cpu/arm7_common/arm_cpu.c
index 6d5c4173d..f6957bdcf 100644
--- a/cpu/arm7_common/arm_cpu.c
+++ b/cpu/arm7_common/arm_cpu.c
@@ -28,25 +28,6 @@ void thread_yield_higher(void)
     __asm__("svc 0\n");
 }
 
-/* This function calculates the ISR_usage */
-int thread_arch_isr_stack_usage(void)
-{
-    /* TODO */
-    return -1;
-}
-
-void *thread_arch_isr_stack_pointer(void)
-{
-    /* TODO */
-    return (void *)-1;
-}
-
-void *thread_arch_isr_stack_start(void)
-{
-    /* TODO */
-    return (void *)-1;
-}
-
 /*----------------------------------------------------------------------------
  * Processor specific routine - here for ARM7
  * sizeof(void*) = sizeof(int)
diff --git a/cpu/atmega1281/include/cpu_conf.h b/cpu/atmega1281/include/cpu_conf.h
index ccad511d0..49d826682 100644
--- a/cpu/atmega1281/include/cpu_conf.h
+++ b/cpu/atmega1281/include/cpu_conf.h
@@ -41,10 +41,6 @@ extern "C" {
 #ifndef THREAD_STACKSIZE_IDLE
 #   define THREAD_STACKSIZE_IDLE      (128)
 #endif
-
-#ifndef ISR_STACKSIZE
-#   define ISR_STACKSIZE              (0)
-#endif
 /** @} */
 
 #ifdef __cplusplus
diff --git a/cpu/atmega2560/include/cpu_conf.h b/cpu/atmega2560/include/cpu_conf.h
index 7216b2800..acf443981 100644
--- a/cpu/atmega2560/include/cpu_conf.h
+++ b/cpu/atmega2560/include/cpu_conf.h
@@ -40,7 +40,6 @@ extern "C" {
 #endif
 
 #define THREAD_STACKSIZE_IDLE      (128)
-#define ISR_STACKSIZE              (0)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/cpu/atmega328p/include/cpu_conf.h b/cpu/atmega328p/include/cpu_conf.h
index fd6b7a337..4b35944ce 100644
--- a/cpu/atmega328p/include/cpu_conf.h
+++ b/cpu/atmega328p/include/cpu_conf.h
@@ -40,7 +40,6 @@ extern "C" {
 #endif
 
 #define THREAD_STACKSIZE_IDLE      (128)
-#define ISR_STACKSIZE              (0)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/cpu/atmega_common/thread_arch.c b/cpu/atmega_common/thread_arch.c
index 0193dd545..ed4d79e90 100644
--- a/cpu/atmega_common/thread_arch.c
+++ b/cpu/atmega_common/thread_arch.c
@@ -223,25 +223,6 @@ void thread_arch_stack_print(void)
     printf("stack size: %u bytes\n", size);
 }
 
-/* This function calculates the ISR_usage */
-int thread_arch_isr_stack_usage(void)
-{
-    /* TODO */
-    return -1;
-}
-
-void *thread_arch_isr_stack_pointer(void)
-{
-    /* TODO */
-    return (void *)-1;
-}
-
-void *thread_arch_isr_stack_start(void)
-{
-    /* TODO */
-    return (void *)-1;
-}
-
 void thread_arch_start_threading(void) __attribute__((naked));
 void thread_arch_start_threading(void)
 {
diff --git a/cpu/lpc2387/include/cpu_conf.h b/cpu/lpc2387/include/cpu_conf.h
index f6e84f4db..a50a5ee24 100644
--- a/cpu/lpc2387/include/cpu_conf.h
+++ b/cpu/lpc2387/include/cpu_conf.h
@@ -51,8 +51,6 @@ extern "C" {
 #endif
 
 #define THREAD_STACKSIZE_IDLE      (160)
-
-#define ISR_STACKSIZE              (0)
 /** @} */
 
 /**
diff --git a/cpu/mips32r2_common/include/cpu_conf.h b/cpu/mips32r2_common/include/cpu_conf.h
index 46afd1759..74fa00c7d 100644
--- a/cpu/mips32r2_common/include/cpu_conf.h
+++ b/cpu/mips32r2_common/include/cpu_conf.h
@@ -57,8 +57,6 @@ extern "C" {
 #define THREAD_STACKSIZE_IDLE           (512 + THREAD_EXTRA_STACKSIZE_PRINTF)
 #endif
 #endif
-
-#define ISR_STACKSIZE                   (0)
 /** @} */
 
 
diff --git a/cpu/mips32r2_common/thread_arch.c b/cpu/mips32r2_common/thread_arch.c
index 69b8fbb94..1210f99f0 100644
--- a/cpu/mips32r2_common/thread_arch.c
+++ b/cpu/mips32r2_common/thread_arch.c
@@ -117,26 +117,6 @@ void thread_arch_stack_print(void)
     }
 }
 
-
-/* This function calculates the ISR_usage */
-int thread_arch_isr_stack_usage(void)
-{
-    /* TODO */
-    return -1;
-}
-
-void *thread_arch_isr_stack_pointer(void)
-{
-    /* TODO */
-    return (void *)-1;
-}
-
-void *thread_arch_isr_stack_start(void)
-{
-    /* TODO */
-    return (void *)-1;
-}
-
 extern void __exception_restore(void);
 void thread_arch_start_threading(void)
 {
diff --git a/cpu/mips_pic32mx/include/cpu_conf.h b/cpu/mips_pic32mx/include/cpu_conf.h
index 088574519..6ef3af3e1 100644
--- a/cpu/mips_pic32mx/include/cpu_conf.h
+++ b/cpu/mips_pic32mx/include/cpu_conf.h
@@ -58,8 +58,6 @@ extern "C" {
 #define THREAD_STACKSIZE_IDLE           (512 + THREAD_EXTRA_STACKSIZE_PRINTF)
 #endif
 #endif
-
-#define ISR_STACKSIZE                   (0)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/cpu/mips_pic32mz/include/cpu_conf.h b/cpu/mips_pic32mz/include/cpu_conf.h
index 5d69e7fbf..f2bd99554 100644
--- a/cpu/mips_pic32mz/include/cpu_conf.h
+++ b/cpu/mips_pic32mz/include/cpu_conf.h
@@ -59,8 +59,6 @@ extern "C" {
 #define THREAD_STACKSIZE_IDLE           (512 + THREAD_EXTRA_STACKSIZE_PRINTF)
 #endif
 #endif
-
-#define ISR_STACKSIZE                   (0)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/cpu/msp430_common/cpu.c b/cpu/msp430_common/cpu.c
index 2cd45e76b..3bc28efbe 100644
--- a/cpu/msp430_common/cpu.c
+++ b/cpu/msp430_common/cpu.c
@@ -52,6 +52,7 @@ void *thread_arch_isr_stack_start(void)
     return (void *)-1;
 }
 
+
 NORETURN void cpu_switch_context_exit(void)
 {
     sched_active_thread = sched_threads[0];
diff --git a/cpu/x86/x86_thread_arch.c b/cpu/x86/x86_thread_arch.c
deleted file mode 100644
index bcd494d15..000000000
--- a/cpu/x86/x86_thread_arch.c
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * Copyright (C) 2016 Freie Universität Berlin
- *
- * This file is subject to the terms and conditions of the GNU Lesser
- * General Public License v2.1. See the file LICENSE in the top level
- * directory for more details.
- */
-
-/**
- * @{
- *
- * @file
- * @author  Martine Lenders <mlenders@inf.fu-berlin.de>
- */
-
-#include "arch/thread_arch.h"
-
-/* This function calculates the ISR_usage */
-int thread_arch_isr_stack_usage(void)
-{
-    /* TODO */
-    return -1;
-}
-
-/** @} */
diff --git a/sys/ps/ps.c b/sys/ps/ps.c
index 34778c2b1..f3042c4de 100644
--- a/sys/ps/ps.c
+++ b/sys/ps/ps.c
@@ -72,7 +72,7 @@ void ps(void)
 #endif
            "state");
 
-#ifdef DEVELHELP
+#if defined(DEVELHELP) && defined(ISR_STACKSIZE)
     int isr_usage = thread_arch_isr_stack_usage();
     void *isr_start = thread_arch_isr_stack_start();
     void *isr_sp = thread_arch_isr_stack_pointer();