diff --git a/ports/ARM7-LPC214x/chcore.c b/ports/ARM7-LPC214x/chcore.c
index 858214ea3..dd65e87eb 100644
--- a/ports/ARM7-LPC214x/chcore.c
+++ b/ports/ARM7-LPC214x/chcore.c
@@ -54,9 +54,7 @@ void sys_wait_for_interrupt(void) {
 }
 
 /**
- * Halts the system. This function is invoked by the operating system when an
- * unrecoverable error is detected (as example because a programming error in
- * the application code that triggers an assertion while in debug mode).
+ * Halts the system.
  */
 __attribute__((weak))
 void sys_halt(void) {
diff --git a/ports/ARMCM3/chcore.c b/ports/ARMCM3/chcore.c
index 6b4811904..a6871d701 100644
--- a/ports/ARMCM3/chcore.c
+++ b/ports/ARMCM3/chcore.c
@@ -36,25 +36,28 @@ __attribute__((weak))
 void sys_puts(char *msg) {
 }
 
+/**
+ * Halts the system.
+ * @note The function is declared as a weak symbol, it is possible to redefine
+ *       it in your application code.
+ */
+__attribute__((weak))
 void sys_halt(void) {
 
-  asm volatile ("cpsid   i");
+  sys_disable_all();
   while (TRUE) {
   }
 }
 
 /**
  * Start a thread by invoking its work function.
- * If the work function returns @p chThdExit() is automatically invoked. A call
- * to @p chSysHalt() is added as failure check in the "impossible" case
- * @p chThdExit() returns.
+ * If the work function returns @p chThdExit() is automatically invoked.
  */
 __attribute__((naked, weak))
 void threadstart(void) {
 
   asm volatile ("blx     r1                                     \n\t" \
-                "bl      chThdExit                              \n\t" \
-                "bl      chSysHalt                              ");
+                "bl      chThdExit");
 }
 
 /**
diff --git a/ports/ARMCM3/chcore.h b/ports/ARMCM3/chcore.h
index c213b9ffd..a0f0c4f4e 100644
--- a/ports/ARMCM3/chcore.h
+++ b/ports/ARMCM3/chcore.h
@@ -186,6 +186,13 @@ typedef struct {
  */
 #define sys_enable_from_isr() sys_enable()
 
+/**
+ * Disables all the interrupt sources, even those having a priority higher
+ * to the kernel.
+ * In the Cortex-M3 it raises the priority mask to level 0.
+ */
+#define sys_disable_all() asm volatile ("cpsid   i")
+
 #if ENABLE_WFI_IDLE != 0
 /**
  * This port function is implemented as inlined code for performance reasons.
diff --git a/ports/ARMCM3/crt0.s b/ports/ARMCM3/crt0.s
index b59f0993b..06bbb49c6 100644
--- a/ports/ARMCM3/crt0.s
+++ b/ports/ARMCM3/crt0.s
@@ -95,7 +95,7 @@ bloop:
         movs    r0, #0
         mov     r1, r0
         bl      main
-        bl      chSysHalt
+        bl      sys_halt
 
 /*
  * Default early initialization code. It is declared weak in order to be
@@ -108,7 +108,7 @@ bloop:
 .weak hwinit0
 hwinit0:
         bx      lr
-        
+
 /*
  * Default late initialization code. It is declared weak in order to be
  * replaced by the real initialization code.
diff --git a/src/include/sys.h b/src/include/sys.h
index cf7cf78a4..25cdbed6a 100644
--- a/src/include/sys.h
+++ b/src/include/sys.h
@@ -32,8 +32,9 @@
 #define chSysPuts(msg) sys_puts(msg)
 
 /**
- * Abonormal system termination handler. Invoked by the ChibiOS/RT when an
- * abnormal unrecoverable condition is met.
+ * Halts the system. This function is invoked by the operating system when an
+ * unrecoverable error is detected (as example because a programming error in
+ * the application code that triggers an assertion while in debug mode).
  */
 #define chSysHalt() sys_halt()