diff --git a/include/strings.h b/include/strings.h
index 17543569236..72ea016d748 100644
--- a/include/strings.h
+++ b/include/strings.h
@@ -55,10 +55,17 @@
  * Removed from Open Group Base Specifications Issue 7/
  * IEEE Std 1003.1-2008
  */
-
+#ifndef bcmp
 #define bcmp(b1,b2,len)  memcmp(b1,b2,(size_t)len)
+#endif
+
+#ifndef bcopy
 #define bcopy(b1,b2,len) (void)memmove(b2,b1,len)
+#endif
+
+#ifndef bzero
 #define bzero(s,n)       (void)memset(s,0,n)
+#endif
 
 /****************************************************************************
  * Inline Functions
diff --git a/libs/libc/stdlib/lib_atoi.c b/libs/libc/stdlib/lib_atoi.c
index 916dec70e16..1a9496db2f5 100644
--- a/libs/libc/stdlib/lib_atoi.c
+++ b/libs/libc/stdlib/lib_atoi.c
@@ -28,6 +28,7 @@
  * Public Functions
  ****************************************************************************/
 
+#undef atoi
 int atoi(FAR const char *nptr)
 {
   return strtol(nptr, NULL, 10);
diff --git a/libs/libc/stdlib/lib_atol.c b/libs/libc/stdlib/lib_atol.c
index e3f20643012..8d8b2ac04fc 100644
--- a/libs/libc/stdlib/lib_atol.c
+++ b/libs/libc/stdlib/lib_atol.c
@@ -28,6 +28,7 @@
  * Public Functions
  ****************************************************************************/
 
+#undef atol
 long atol(FAR const char *nptr)
 {
   return strtol(nptr, NULL, 10);
diff --git a/libs/libc/string/lib_index.c b/libs/libc/string/lib_index.c
index 9056b5f18ae..b3c123d15b6 100644
--- a/libs/libc/string/lib_index.c
+++ b/libs/libc/string/lib_index.c
@@ -32,6 +32,7 @@
  * Name: index
  ****************************************************************************/
 
+#undef index
 FAR char *index(FAR const char *s, int c)
 {
   return strchr(s, c);
diff --git a/libs/libc/string/lib_memccpy.c b/libs/libc/string/lib_memccpy.c
index 5f712771bce..e7b03ca8f0e 100644
--- a/libs/libc/string/lib_memccpy.c
+++ b/libs/libc/string/lib_memccpy.c
@@ -62,6 +62,7 @@
  *
  ****************************************************************************/
 
+#undef memccpy
 FAR void *memccpy(FAR void *s1, FAR const void *s2, int c, size_t n)
 {
   FAR unsigned char *pout = (FAR unsigned char *)s1;
diff --git a/libs/libc/string/lib_memchr.c b/libs/libc/string/lib_memchr.c
index 5b1facabad7..c9a951543a9 100644
--- a/libs/libc/string/lib_memchr.c
+++ b/libs/libc/string/lib_memchr.c
@@ -59,6 +59,7 @@
  *
  ****************************************************************************/
 
+#undef memchr
 FAR void *memchr(FAR const void *s, int c, size_t n)
 {
   FAR const unsigned char *p = (FAR const unsigned char *)s;
diff --git a/libs/libc/string/lib_memcmp.c b/libs/libc/string/lib_memcmp.c
index c17149fbfdb..522f8b001fa 100644
--- a/libs/libc/string/lib_memcmp.c
+++ b/libs/libc/string/lib_memcmp.c
@@ -46,6 +46,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_MEMCMP
+#undef memcmp
 int memcmp(FAR const void *s1, FAR const void *s2, size_t n)
 {
   unsigned char *p1 = (unsigned char *)s1;
diff --git a/libs/libc/string/lib_memcpy.c b/libs/libc/string/lib_memcpy.c
index 8fbeb0644bd..ca5ddf05b1a 100644
--- a/libs/libc/string/lib_memcpy.c
+++ b/libs/libc/string/lib_memcpy.c
@@ -50,6 +50,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_MEMCPY
+#undef memcpy
 FAR void *memcpy(FAR void *dest, FAR const void *src, size_t n)
 {
   FAR unsigned char *pout = (FAR unsigned char *)dest;
diff --git a/libs/libc/string/lib_memmove.c b/libs/libc/string/lib_memmove.c
index f8c4e890d30..96c6bdd1c7c 100644
--- a/libs/libc/string/lib_memmove.c
+++ b/libs/libc/string/lib_memmove.c
@@ -46,6 +46,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_MEMMOVE
+#undef memmove
 FAR void *memmove(FAR void *dest, FAR const void *src, size_t count)
 {
   FAR char *tmp;
diff --git a/libs/libc/string/lib_memset.c b/libs/libc/string/lib_memset.c
index da3d4ada80d..a29e3eefaaf 100644
--- a/libs/libc/string/lib_memset.c
+++ b/libs/libc/string/lib_memset.c
@@ -63,6 +63,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_MEMSET
+#undef memset
 FAR void *memset(FAR void *s, int c, size_t n)
 {
 #ifdef CONFIG_MEMSET_OPTSPEED
diff --git a/libs/libc/string/lib_rindex.c b/libs/libc/string/lib_rindex.c
index 9be145e312f..10fceab0d32 100644
--- a/libs/libc/string/lib_rindex.c
+++ b/libs/libc/string/lib_rindex.c
@@ -32,6 +32,7 @@
  * Name: rindex
  ****************************************************************************/
 
+#undef rindex
 FAR char *rindex(FAR const char *s, int c)
 {
   return strrchr(s, c);
diff --git a/libs/libc/string/lib_strcasecmp.c b/libs/libc/string/lib_strcasecmp.c
index a8b6ae8ea87..6361bf4e631 100644
--- a/libs/libc/string/lib_strcasecmp.c
+++ b/libs/libc/string/lib_strcasecmp.c
@@ -47,6 +47,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_ARCH_STRCASECMP
+#undef strcasecmp
 int strcasecmp(FAR const char *cs, FAR const char *ct)
 {
   int result;
diff --git a/libs/libc/string/lib_strcat.c b/libs/libc/string/lib_strcat.c
index 18a70d8966e..e2058bdb024 100644
--- a/libs/libc/string/lib_strcat.c
+++ b/libs/libc/string/lib_strcat.c
@@ -46,6 +46,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_ARCH_STRCAT
+#undef strcat
 char *strcat(char *dest, const char *src)
 {
   char *ret   = dest;
diff --git a/libs/libc/string/lib_strchr.c b/libs/libc/string/lib_strchr.c
index c86e0468522..0d40e7ac8c7 100644
--- a/libs/libc/string/lib_strchr.c
+++ b/libs/libc/string/lib_strchr.c
@@ -60,6 +60,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_STRCHR
+#undef strchr
 FAR char *strchr(FAR const char *s, int c)
 {
   if (s)
diff --git a/libs/libc/string/lib_strcmp.c b/libs/libc/string/lib_strcmp.c
index dab875ce709..c1129c7f040 100644
--- a/libs/libc/string/lib_strcmp.c
+++ b/libs/libc/string/lib_strcmp.c
@@ -46,6 +46,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_STRCMP
+#undef strcmp
 int strcmp(FAR const char *cs, FAR const char *ct)
 {
   register signed char result;
diff --git a/libs/libc/string/lib_strcpy.c b/libs/libc/string/lib_strcpy.c
index 864e417fada..0b9dc80ce87 100644
--- a/libs/libc/string/lib_strcpy.c
+++ b/libs/libc/string/lib_strcpy.c
@@ -58,6 +58,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_STRCPY
+#undef strcpy
 FAR char *strcpy(FAR char *dest, FAR const char *src)
 {
   char *tmp = dest;
diff --git a/libs/libc/string/lib_strcspn.c b/libs/libc/string/lib_strcspn.c
index 431d8d4fee9..19e165486c0 100644
--- a/libs/libc/string/lib_strcspn.c
+++ b/libs/libc/string/lib_strcspn.c
@@ -54,6 +54,7 @@
  *
  ****************************************************************************/
 
+#undef strcspn
 size_t strcspn(const char *s, const char *reject)
 {
   size_t i;
diff --git a/libs/libc/string/lib_strdup.c b/libs/libc/string/lib_strdup.c
index 1d88195ae9d..ea8b82fd162 100644
--- a/libs/libc/string/lib_strdup.c
+++ b/libs/libc/string/lib_strdup.c
@@ -47,6 +47,7 @@
  * Public Functions
  ****************************************************************************/
 
+#undef strdup
 FAR char *strdup(FAR const char *s)
 {
   FAR char *news = NULL;
diff --git a/libs/libc/string/lib_strlen.c b/libs/libc/string/lib_strlen.c
index 6e29a434b04..f7758c9a802 100644
--- a/libs/libc/string/lib_strlen.c
+++ b/libs/libc/string/lib_strlen.c
@@ -46,6 +46,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_STRLEN
+#undef strlen
 size_t strlen(const char *s)
 {
   const char *sc;
diff --git a/libs/libc/string/lib_strncasecmp.c b/libs/libc/string/lib_strncasecmp.c
index 82a15b2491c..88a6391f44a 100644
--- a/libs/libc/string/lib_strncasecmp.c
+++ b/libs/libc/string/lib_strncasecmp.c
@@ -48,6 +48,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_ARCH_STRNCASECMP
+#undef strncasecmp
 int strncasecmp(const char *cs, const char *ct, size_t nb)
 {
   int result = 0;
diff --git a/libs/libc/string/lib_strncat.c b/libs/libc/string/lib_strncat.c
index 152ca32da0b..b27f3ebbff7 100644
--- a/libs/libc/string/lib_strncat.c
+++ b/libs/libc/string/lib_strncat.c
@@ -46,6 +46,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_ARCH_STRNCAT
+#undef strncat
 char *strncat(char *dest, const char *src, size_t n)
 {
   char *ret   = dest;
diff --git a/libs/libc/string/lib_strncmp.c b/libs/libc/string/lib_strncmp.c
index 0aadda5c4b1..c08170893ae 100644
--- a/libs/libc/string/lib_strncmp.c
+++ b/libs/libc/string/lib_strncmp.c
@@ -46,6 +46,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_ARCH_STRNCMP
+#undef strncmp
 int strncmp(const char *cs, const char *ct, size_t nb)
 {
   int result = 0;
diff --git a/libs/libc/string/lib_strncpy.c b/libs/libc/string/lib_strncpy.c
index b0263524eb8..3f9145b3423 100644
--- a/libs/libc/string/lib_strncpy.c
+++ b/libs/libc/string/lib_strncpy.c
@@ -67,6 +67,7 @@
  ****************************************************************************/
 
 #ifndef CONFIG_LIBC_ARCH_STRNCPY
+#undef strncpy
 FAR char *strncpy(FAR char *dest, FAR const char *src, size_t n)
 {
   FAR char *ret = dest;     /* Value to be returned */
diff --git a/libs/libc/string/lib_strndup.c b/libs/libc/string/lib_strndup.c
index a071d188627..ae54f918f23 100644
--- a/libs/libc/string/lib_strndup.c
+++ b/libs/libc/string/lib_strndup.c
@@ -63,6 +63,7 @@
  *
  ****************************************************************************/
 
+#undef strndup
 FAR char *strndup(FAR const char *s, size_t size)
 {
   FAR char *news = NULL;
diff --git a/libs/libc/string/lib_strpbrk.c b/libs/libc/string/lib_strpbrk.c
index 6e7ab63d0c2..f74a241981a 100644
--- a/libs/libc/string/lib_strpbrk.c
+++ b/libs/libc/string/lib_strpbrk.c
@@ -45,6 +45,7 @@
  * Public Functions
  ****************************************************************************/
 
+#undef strpbrk
 FAR char *strpbrk(FAR const char *str, FAR const char *charset)
 {
   /* Sanity checking */
diff --git a/libs/libc/string/lib_strrchr.c b/libs/libc/string/lib_strrchr.c
index 8e96d81c9d0..da22bd0849e 100644
--- a/libs/libc/string/lib_strrchr.c
+++ b/libs/libc/string/lib_strrchr.c
@@ -49,6 +49,7 @@
  * occurrence of the character c in the string s.
  */
 
+#undef strrchr
 FAR char *strrchr(FAR const char *s, int c)
 {
   if (s)
diff --git a/libs/libc/string/lib_strspn.c b/libs/libc/string/lib_strspn.c
index 3804bdfc281..ce10c197a15 100644
--- a/libs/libc/string/lib_strspn.c
+++ b/libs/libc/string/lib_strspn.c
@@ -54,6 +54,7 @@
  *
  ****************************************************************************/
 
+#undef strspn
 size_t strspn(const char *s, const char *accept)
 {
   size_t i;
diff --git a/libs/libc/string/lib_strstr.c b/libs/libc/string/lib_strstr.c
index 5253ed02aca..18c7605b067 100644
--- a/libs/libc/string/lib_strstr.c
+++ b/libs/libc/string/lib_strstr.c
@@ -57,6 +57,7 @@
  * string haystack. Returns NULL if needle was not found.
  */
 
+#undef strstr
 FAR char *strstr(FAR const char *haystack, FAR const char *needle)
 {
 #ifndef ULONG_BIGENDIAN
diff --git a/libs/libc/string/lib_strtok.c b/libs/libc/string/lib_strtok.c
index 8c39a635130..3a747183a0e 100644
--- a/libs/libc/string/lib_strtok.c
+++ b/libs/libc/string/lib_strtok.c
@@ -81,6 +81,7 @@ static char *g_saveptr = NULL;
  *
  ****************************************************************************/
 
+#undef strtok
 char *strtok(char *str, const char *delim)
 {
   return strtok_r(str, delim, &g_saveptr);