diff --git a/core/include/sched.h b/core/include/sched.h
index c905573d22..8332a1a9be 100644
--- a/core/include/sched.h
+++ b/core/include/sched.h
@@ -55,9 +55,8 @@ void sched_set_status(tcb_t *process, unsigned int status);
  *
  * @param[in]   current_prio    The priority of the current thread
  * @param[in]   other_prio      The priority of the target thread
- * @param[in]   in_isr          1 if currently in interrupt context, 0 otherwise
  */
-void sched_switch(uint16_t current_prio, uint16_t other_prio, int in_isr);
+void sched_switch(uint16_t current_prio, uint16_t other_prio);
 
 /**
  * @brief   Call context switching at task exit
diff --git a/core/mutex.c b/core/mutex.c
index ece0b0118b..664b864df4 100644
--- a/core/mutex.c
+++ b/core/mutex.c
@@ -108,7 +108,7 @@ void mutex_unlock(struct mutex_t *mutex)
             DEBUG("%s: waking up waiter.\n", process->name);
             sched_set_status(process, STATUS_PENDING);
 
-            sched_switch(active_thread->priority, process->priority, inISR());
+            sched_switch(active_thread->priority, process->priority);
         }
         else {
             mutex->val = 0;
diff --git a/core/sched.c b/core/sched.c
index 90556603cb..1863d197e3 100644
--- a/core/sched.c
+++ b/core/sched.c
@@ -171,8 +171,10 @@ void sched_set_status(tcb_t *process, unsigned int status)
     process->status = status;
 }
 
-void sched_switch(uint16_t current_prio, uint16_t other_prio, int in_isr)
+void sched_switch(uint16_t current_prio, uint16_t other_prio)
 {
+    int in_isr = inISR();
+
     DEBUG("%s: %i %i %i\n", active_thread->name, (int)current_prio, (int)other_prio, in_isr);
 
     if (current_prio >= other_prio) {
diff --git a/sys/posix/pthread/pthread.c b/sys/posix/pthread/pthread.c
index 222e341167..f3fb22d807 100644
--- a/sys/posix/pthread/pthread.c
+++ b/sys/posix/pthread/pthread.c
@@ -152,7 +152,7 @@ int pthread_create(pthread_t *newthread, const pthread_attr_t *attr, void *(*sta
         return -1;
     }
 
-    sched_switch(active_thread->priority, PRIORITY_MAIN, inISR());
+    sched_switch(active_thread->priority, PRIORITY_MAIN);
 
     return 0;
 }
diff --git a/sys/semaphore/semaphore.c b/sys/semaphore/semaphore.c
index 7e155547a0..6276226e88 100644
--- a/sys/semaphore/semaphore.c
+++ b/sys/semaphore/semaphore.c
@@ -145,7 +145,7 @@ int sem_post(sem_t *sem)
         tcb_t *next_process = (tcb_t*) next->data;
         DEBUG("%s: waking up %s\n", active_thread->name, next_process->name);
         sched_set_status(next_process, STATUS_PENDING);
-        sched_switch(active_thread->priority, next_process->priority, inISR());
+        sched_switch(active_thread->priority, next_process->priority);
     }
 
     restoreIRQ(old_state);