diff --git a/os/nil/ports/ARMCMx/nilcore.c b/os/nil/ports/ARMCMx/nilcore.c
index c66ce160c..e50dc5b80 100644
--- a/os/nil/ports/ARMCMx/nilcore.c
+++ b/os/nil/ports/ARMCMx/nilcore.c
@@ -19,14 +19,14 @@
 */
 
 /**
- * @file    ARMCMx/chcore.c
+ * @file    ARMCMx/nilcore.c
  * @brief   ARM Cortex-Mx port code.
  *
  * @addtogroup ARMCMx_CORE
  * @{
  */
 
-#include "ch.h"
+#include "nil.h"
 
 /*===========================================================================*/
 /* Module local definitions.                                                 */
@@ -52,4 +52,19 @@
 /* Module exported functions.                                                */
 /*===========================================================================*/
 
+/**
+ * @brief   Halts the system.
+ * @note    The function is declared as a weak symbol, it is possible
+ *          to redefine it in your application code.
+ */
+#if !defined(__DOXYGEN__)
+__attribute__((naked, weak))
+#endif
+void port_halt(void) {
+
+  port_disable();
+  while (true) {
+  }
+}
+
 /** @} */
diff --git a/os/nil/ports/ARMCMx/nilcore.h b/os/nil/ports/ARMCMx/nilcore.h
index c2eb68078..9a31f5c87 100644
--- a/os/nil/ports/ARMCMx/nilcore.h
+++ b/os/nil/ports/ARMCMx/nilcore.h
@@ -19,15 +19,15 @@
 */
 
 /**
- * @file    ARMCMx/chcore.h
+ * @file    ARMCMx/nilcore.h
  * @brief   ARM Cortex-Mx port macros and structures.
  *
  * @addtogroup ARMCMx_CORE
  * @{
  */
 
-#ifndef _CHCORE_H_
-#define _CHCORE_H_
+#ifndef _NILCORE_H_
+#define _NILCORE_H_
 
 /*===========================================================================*/
 /* Module constants.                                                         */
@@ -191,11 +191,11 @@ struct port_intctx {};
 /* Includes the sub-architecture-specific part.*/
 #if (CORTEX_MODEL == CORTEX_M0) || (CORTEX_MODEL == CORTEX_M0PLUS) ||       \
     (CORTEX_MODEL == CORTEX_M1)
-#include "chcore_v6m.h"
+#include "nilcore_v6m.h"
 #elif (CORTEX_MODEL == CORTEX_M3) || (CORTEX_MODEL == CORTEX_M4)
-#include "chcore_v7m.h"
+#include "nilcore_v7m.h"
 #endif
 
-#endif /* _CHCORE_H_ */
+#endif /* _NILCORE_H_ */
 
 /** @} */
diff --git a/os/nil/ports/ARMCMx/nilcore_timer.h b/os/nil/ports/ARMCMx/nilcore_timer.h
index 166610b2c..9079dea8c 100644
--- a/os/nil/ports/ARMCMx/nilcore_timer.h
+++ b/os/nil/ports/ARMCMx/nilcore_timer.h
@@ -19,7 +19,7 @@
 */
 
 /**
- * @file    ARMCMx/chcore_timer.h
+ * @file    ARMCMx/nilcore_timer.h
  * @brief   System timer header file.
  *
  * @addtogroup ARMCMx_TIMER
@@ -33,7 +33,7 @@
 /* If, for some reason, the use of the HAL-provided ST timer port interface
    is not wanted, it is possible to provide the timer interface into a custom
    module.*/
-#include "chcore_timer_ext.h"
+#include "nilcore_timer_ext.h"
 
 #else /* !defined(PORT_DO_NOT_USE_ST) */
 
diff --git a/os/nil/ports/ARMCMx/nilcore_v6m.c b/os/nil/ports/ARMCMx/nilcore_v6m.c
index 78e796087..d8772ca54 100644
--- a/os/nil/ports/ARMCMx/nilcore_v6m.c
+++ b/os/nil/ports/ARMCMx/nilcore_v6m.c
@@ -19,14 +19,14 @@
 */
 
 /**
- * @file    ARMCMx/chcore_v6m.c
+ * @file    ARMCMx/nilcore_v6m.c
  * @brief   ARMv6-M architecture port code.
  *
  * @addtogroup ARMCMx_V6M_CORE
  * @{
  */
 
-#include "ch.h"
+#include "nil.h"
 
 /*===========================================================================*/
 /* Module local definitions.                                                 */
@@ -124,17 +124,8 @@ void _port_irq_epilogue(regarm_t lr) {
     /* Setting up a fake XPSR register value.*/
     ctxp->xpsr = (regarm_t)0x01000000;
 
-    /* The exit sequence is different depending on if a preemption is
-       required or not.*/
-    if (chSchIsPreemptionRequired()) {
-      /* Preemption is required we need to enforce a context switch.*/
-      ctxp->pc = (void *)_port_switch_from_isr;
-    }
-    else {
-      /* Preemption not required, we just need to exit the exception
-         atomically.*/
-      ctxp->pc = (void *)_port_exit_from_isr;
-    }
+    /* The context switch is handled outside the ISR context..*/
+    ctxp->pc = (regarm_t)_port_switch_from_isr;
 
     /* Note, returning without unlocking is intentional, this is done in
        order to keep the rest of the context switch atomic.*/
diff --git a/os/rt/ports/ARMCMx/chcore_v6m.c b/os/rt/ports/ARMCMx/chcore_v6m.c
index 78e796087..4886496da 100644
--- a/os/rt/ports/ARMCMx/chcore_v6m.c
+++ b/os/rt/ports/ARMCMx/chcore_v6m.c
@@ -128,12 +128,12 @@ void _port_irq_epilogue(regarm_t lr) {
        required or not.*/
     if (chSchIsPreemptionRequired()) {
       /* Preemption is required we need to enforce a context switch.*/
-      ctxp->pc = (void *)_port_switch_from_isr;
+      ctxp->pc = (regarm_t)_port_switch_from_isr;
     }
     else {
       /* Preemption not required, we just need to exit the exception
          atomically.*/
-      ctxp->pc = (void *)_port_exit_from_isr;
+      ctxp->pc = (regarm_t)_port_exit_from_isr;
     }
 
     /* Note, returning without unlocking is intentional, this is done in
diff --git a/os/rt/ports/ARMCMx/chcore_v7m.c b/os/rt/ports/ARMCMx/chcore_v7m.c
index 4cd5db64a..49826c48c 100644
--- a/os/rt/ports/ARMCMx/chcore_v7m.c
+++ b/os/rt/ports/ARMCMx/chcore_v7m.c
@@ -138,7 +138,7 @@ void _port_irq_epilogue(void) {
        required or not.*/
     if (chSchIsPreemptionRequired()) {
       /* Preemption is required we need to enforce a context switch.*/
-      ctxp->pc = (void *)_port_switch_from_isr;
+      ctxp->pc = (regarm_t)_port_switch_from_isr;
 #if CORTEX_USE_FPU
       /* Enforcing a lazy FPU state save by accessing the FPCSR register.*/
       (void) __get_FPSCR();
@@ -147,7 +147,7 @@ void _port_irq_epilogue(void) {
     else {
       /* Preemption not required, we just need to exit the exception
          atomically.*/
-      ctxp->pc = (void *)_port_exit_from_isr;
+      ctxp->pc = (regarm_t)_port_exit_from_isr;
     }
 
 #if CORTEX_USE_FPU