diff --git a/os/common/ports/ARMCMx/chcore_v7m.c b/os/common/ports/ARMCMx/chcore_v7m.c
index 5b1816c81..77038eb47 100644
--- a/os/common/ports/ARMCMx/chcore_v7m.c
+++ b/os/common/ports/ARMCMx/chcore_v7m.c
@@ -301,7 +301,7 @@ void port_init(os_instance_t *oip) {
 /**
  * @brief   Setting up MPU region for the current thread.
  */
-void _port_set_region(void) {
+void __port_set_region(void) {
 
   mpuSetRegionAddress(PORT_USE_GUARD_MPU_REGION,
                       chThdGetSelfX()->wabase);
diff --git a/os/common/ports/ARMCMx/chcore_v7m.h b/os/common/ports/ARMCMx/chcore_v7m.h
index 02995a63f..e5712fac5 100644
--- a/os/common/ports/ARMCMx/chcore_v7m.h
+++ b/os/common/ports/ARMCMx/chcore_v7m.h
@@ -578,11 +578,11 @@ struct port_context {
   if ((stkalign_t *)(r13 - 1) < (otp)->wabase) {                            \
     chSysHalt("stack overflow");                                            \
   }                                                                         \
-  __port_switch(ntp, otp);                                                   \
+  __port_switch(ntp, otp);                                                  \
 }
 #else
 #define port_switch(ntp, otp) {                                             \
-  _port_switch(ntp, otp);                                                   \
+  __port_switch(ntp, otp);                                                  \
                                                                             \
   /* Setting up the guard page for the switched-in thread.*/                \
   mpuSetRegionAddress(PORT_USE_GUARD_MPU_REGION,                            \
diff --git a/os/various/syscalls.c b/os/various/syscalls.c
index 8da8f755a..b2052e954 100644
--- a/os/various/syscalls.c
+++ b/os/various/syscalls.c
@@ -169,4 +169,29 @@ int _isatty_r(struct _reent *r, int fd) {
   return 1;
 }
 
+/***************************************************************************/
+
+__attribute__((used))
+void _exit(int status) {
+  (void) status;
+  chSysHalt("exit");
+  abort();
+}
+
+/***************************************************************************/
+
+__attribute__((used))
+int _kill(int pid, int sig) {
+  (void) pid;
+  (void) sig;
+  return -1;
+}
+
+/***************************************************************************/
+
+__attribute__((used))
+int _getpid(void) {
+
+  return 1;
+}
 /*** EOF ***/