diff --git a/components/esp8266/include/esp_libc.h b/components/esp8266/include/esp_libc.h
index 98106730..92467def 100644
--- a/components/esp8266/include/esp_libc.h
+++ b/components/esp8266/include/esp_libc.h
@@ -25,52 +25,16 @@
 #ifndef __ESP_LIBC_H__
 #define __ESP_LIBC_H__
 
+#include <stdint.h>
+#include <stddef.h>
+#include <stdio.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-char *strcpy(char *dst, const char *src);
-char *strncpy(char *dst, const char *src, size_t n);
-int strcmp(const char *s1, const char *s2);
-int strncmp(const char *s1, const char *s2, size_t n);
-size_t strlen(const char *s);
-char *strstr(const char *s1, const char *s2);
-char *strcat(char *dst, const char *src);
-char *strncat(char *dst, const char *src, size_t count);
-size_t strspn(const char *s, const char *accept);
-size_t strcspn(const char *s, const char *reject);
-char *strtok_r(char *s, const char *delim, char **ptrptr);
-char *strtok(char *s, const char *delim);
-char *strrchr(const char *s, int c);
-char *strdup(const char *s);
-char *strchr(const char *s, int c);
-long strtol(const char *str, char **endptr, int base);
-
-void bzero(void *s, size_t n);
-
-void *memcpy(void *dst, const void *src, size_t n);
-void *memset(void *dst, int c, size_t n);
-int memcmp(const void *m1, const void *m2, size_t n);
-void *memmove(void *dst, const void *src, size_t n);
-
-int rand(void);
-
-int printf(const char *format, ...);
-int sprintf(char *out, const char *format, ...);
-int snprintf(char *buf, unsigned int count, const char *format, ...);
-int puts(const char *str);
-
-void *malloc(size_t n);
-void free(void *p);
-void *calloc(size_t c, size_t n);
-void *zalloc(size_t n);
-void *realloc(void *p, size_t n);
-
-int atoi(const char *s);
-long atol(const char *s);
-
-unsigned long os_random(void);
-int os_get_random(unsigned char *buf, size_t len);
+uint32_t os_random(void);
+int32_t os_get_random(unsigned char *buf, size_t len);
 
 #ifndef os_printf
 #define os_printf   printf