diff --git a/include/lib/libc/string.h b/include/lib/libc/string.h
index 91cbafb..9894483 100644
--- a/include/lib/libc/string.h
+++ b/include/lib/libc/string.h
@@ -27,5 +27,6 @@
 char *strrchr(const char *p, int ch);
 size_t strlcpy(char * dst, const char * src, size_t dsize);
 size_t strlcat(char * dst, const char * src, size_t dsize);
+char *strtok_r(char *s, const char *delim, char **last);
 
 #endif /* STRING_H */