diff --git a/include/string.h b/include/string.h
index 2aeeba7..bcd188b 100755
--- a/include/string.h
+++ b/include/string.h
@@ -15,7 +15,9 @@
 #include <sys/cdefs.h>
 
 #include <types/size_t.h>
+#ifdef _POSIX_C_SOURCE
 #include <types/locale_t.h>
+#endif
 
 #ifndef NULL
 #define NULL (void *) 0
@@ -25,19 +27,36 @@
 void * memcpy(void * __restrict, const void * __restrict, size_t);
 void * memmove(void *, const void *, size_t);
 
+char * strcpy(char * restrict, const char * restrict);
+char * strncpy(char * restrict, const char * restrict, size_t);
+
 /* Concatenation Functions (ISO C Std. 7.24.3) */
 char * strcat(char * restrict, const char * restrict);
+char * strncat(char * restrict, const char * restrict, size_t);
 
 /* Comparison Functions (ISO C Std. 7.24.4) */
 int memcmp(const void *, const void *, size_t);
 int strcmp(const char *, const char *);
+int strncmp(const char *, const char *, size_t);
+
+int strcoll(const char *, const char *);
+size_t strxfrm(char * restrict, const char * restrict, size_t);
 
 /* Search Functions (ISO C Std. 7.24.5) */
+void * memchr(const void *, int, size_t);
+char * strchr(const char *, int);
+
 size_t strcspn(const char *, const char *);
+char * strpbrk(const char *, const char *);
+char * strrchr(const char *, int);
+size_t strspn(const char *, const char *);
+char * strstr(const char *, const char *);
+
 char * strtok(char * restrict, char * restrict);
 
 /* Miscellaneous Functions (ISO C Std. 7.24.6) */
 void * memset(void *, int, size_t);
+char * strerror(int);
 size_t strlen(const char *);
 
 #endif