diff --git a/py/modsys.c b/py/modsys.c
index d133d6b278..954711a5a9 100644
--- a/py/modsys.c
+++ b/py/modsys.c
@@ -36,11 +36,10 @@
 
 #if MICROPY_ENABLE_MOD_SYS
 
-MP_DECLARE_CONST_FUN_OBJ(mp_sys_exit_obj);
-
 // These should be implemented by ports, specific types don't matter,
 // only addresses.
 struct _dummy_t;
+extern struct _dummy_t mp_sys_exit_obj;
 extern struct _dummy_t mp_sys_stdin_obj;
 extern struct _dummy_t mp_sys_stdout_obj;
 extern struct _dummy_t mp_sys_stderr_obj;
@@ -55,10 +54,6 @@ STATIC const MP_DEFINE_STR_OBJ(version_obj, "3.4.0");
 
 STATIC const mp_map_elem_t mp_module_sys_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_sys) },
-#if MICROPY_SYS_EXIT
-    // Should be implemented by port
-    { MP_OBJ_NEW_QSTR(MP_QSTR_exit), (mp_obj_t)&mp_sys_exit_obj },
-#endif
 
     { MP_OBJ_NEW_QSTR(MP_QSTR_path), (mp_obj_t)&mp_sys_path_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_argv), (mp_obj_t)&mp_sys_argv_obj },
@@ -70,6 +65,10 @@ STATIC const mp_map_elem_t mp_module_sys_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_byteorder), MP_OBJ_NEW_QSTR(MP_QSTR_big) },
 #endif
 
+#if MICROPY_MOD_SYS_EXIT
+    { MP_OBJ_NEW_QSTR(MP_QSTR_exit), (mp_obj_t)&mp_sys_exit_obj },
+#endif
+
 #if MICROPY_MOD_SYS_STDFILES
     { MP_OBJ_NEW_QSTR(MP_QSTR_stdin), (mp_obj_t)&mp_sys_stdin_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_stdout), (mp_obj_t)&mp_sys_stdout_obj },
diff --git a/py/mpconfig.h b/py/mpconfig.h
index a7e1c4a40d..76cd1091cb 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -235,13 +235,14 @@ typedef double mp_float_t;
 #define MICROPY_ENABLE_MOD_SYS (1)
 #endif
 
-#ifndef MICROPY_MOD_SYS_STDFILES
-#define MICROPY_MOD_SYS_STDFILES (0)
+// sys.exit() availability
+#ifndef MICROPY_MOD_SYS_EXIT
+#define MICROPY_MOD_SYS_EXIT (0)
 #endif
 
-// sys.exit() availability
-#ifndef MICROPY_SYS_EXIT
-#define MICROPY_SYS_EXIT (0)
+// sys.{stdin,stdout,stderr} availability
+#ifndef MICROPY_MOD_SYS_STDFILES
+#define MICROPY_MOD_SYS_STDFILES (0)
 #endif
 
 // Whether to support slice object and correspondingly
diff --git a/stmhal/mpconfigport.h b/stmhal/mpconfigport.h
index fd725c67ea..59934b948b 100644
--- a/stmhal/mpconfigport.h
+++ b/stmhal/mpconfigport.h
@@ -45,8 +45,8 @@
 */
 #define MICROPY_ENABLE_LFN          (1)
 #define MICROPY_LFN_CODE_PAGE       (437) /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */
+#define MICROPY_MOD_SYS_EXIT        (1)
 #define MICROPY_MOD_SYS_STDFILES    (1)
-#define MICROPY_SYS_EXIT            (1)
 #define MICROPY_ENABLE_MOD_CMATH    (1)
 
 // extra built in names to add to the global namespace
diff --git a/unix/mpconfigport.h b/unix/mpconfigport.h
index 38bb979c92..4f347f4e02 100644
--- a/unix/mpconfigport.h
+++ b/unix/mpconfigport.h
@@ -42,9 +42,9 @@
 #define MICROPY_PATH_MAX            (PATH_MAX)
 #define MICROPY_STREAMS_NON_BLOCK   (1)
 #define MICROPY_USE_COMPUTED_GOTO   (1)
+#define MICROPY_MOD_SYS_EXIT        (1)
 #define MICROPY_MOD_SYS_STDFILES    (1)
 #define MICROPY_ENABLE_MOD_CMATH    (1)
-#define MICROPY_SYS_EXIT            (1)
 // Define to MICROPY_ERROR_REPORTING_DETAILED to get function, etc.
 // names in exception messages (may require more RAM).
 #define MICROPY_ERROR_REPORTING     (MICROPY_ERROR_REPORTING_DETAILED)