diff --git a/components/esp32/include/rom/libc_stubs.h b/components/esp32/include/rom/libc_stubs.h
index 90c0b44688..6c6366c306 100644
--- a/components/esp32/include/rom/libc_stubs.h
+++ b/components/esp32/include/rom/libc_stubs.h
@@ -75,7 +75,7 @@ struct syscall_stub_table
     int (*_lock_try_acquire_recursive)(_lock_t *lock);
     void (*_lock_release)(_lock_t *lock);
     void (*_lock_release_recursive)(_lock_t *lock);
-    int (*_printf_float)(struct _reent *data, void *pdata, FILE * fp, int (*pfunc) (struct _reent *, FILE *, _CONST char *, size_t len), va_list * ap);
+    int (*_printf_float)(struct _reent *data, void *pdata, FILE * fp, int (*pfunc) (struct _reent *, FILE *, const char *, size_t len), va_list * ap);
     int (*_scanf_float) (struct _reent *rptr, void *pdata, FILE *fp, va_list *ap);
 };
 
diff --git a/components/newlib/platform_include/sys/unistd.h b/components/newlib/platform_include/sys/unistd.h
index e09b68be25..c3149486a2 100644
--- a/components/newlib/platform_include/sys/unistd.h
+++ b/components/newlib/platform_include/sys/unistd.h
@@ -22,8 +22,8 @@ extern "C" {
 
 #include_next <sys/unistd.h>
 
-int     _EXFUN(truncate, (const char *, off_t __length));
-int     _EXFUN(gethostname, (char *__name, size_t __len));
+int truncate(const char *, off_t __length);
+int gethostname(char *__name, size_t __len);
 
 #ifdef __cplusplus
 }
diff --git a/components/newlib/platform_include/time.h b/components/newlib/platform_include/time.h
index 954d824d13..e633bd4ec0 100644
--- a/components/newlib/platform_include/time.h
+++ b/components/newlib/platform_include/time.h
@@ -25,9 +25,9 @@ extern "C" {
 #define CLOCK_MONOTONIC (clockid_t)4
 #define CLOCK_BOOTTIME (clockid_t)4
 
-int _EXFUN(clock_settime, (clockid_t clock_id, const struct timespec *tp));
-int _EXFUN(clock_gettime, (clockid_t clock_id, struct timespec *tp));
-int _EXFUN(clock_getres,  (clockid_t clock_id, struct timespec *res));
+int clock_settime(clockid_t clock_id, const struct timespec *tp);
+int clock_gettime(clockid_t clock_id, struct timespec *tp);
+int clock_getres(clockid_t clock_id, struct timespec *res);
 
 #ifdef __cplusplus
 }
diff --git a/components/newlib/syscall_table.c b/components/newlib/syscall_table.c
index 85a0f125e4..697d050fad 100644
--- a/components/newlib/syscall_table.c
+++ b/components/newlib/syscall_table.c
@@ -32,7 +32,7 @@ static struct _reent s_reent;
 extern int _printf_float(struct _reent *rptr,
                void *pdata,
                FILE * fp,
-               int (*pfunc) (struct _reent *, FILE *, _CONST char *, size_t len),
+               int (*pfunc) (struct _reent *, FILE *, const char *, size_t len),
                va_list * ap);