diff --git a/library/include/errno.h b/library/include/errno.h
index 07a40c1..3fdaffa 100644
--- a/library/include/errno.h
+++ b/library/include/errno.h
@@ -166,6 +166,8 @@ extern int errno;
 
 #define EILSEQ			85	/* Encoding error detected */
 
+#define ENOTSUP			86	/* Not supported */
+
 /****************************************************************************/
 
 #ifdef __cplusplus
diff --git a/library/string_strerror_r.c b/library/string_strerror_r.c
index 48c5e39..885544f 100644
--- a/library/string_strerror_r.c
+++ b/library/string_strerror_r.c
@@ -41,7 +41,7 @@
 
 /****************************************************************************/
 
-static const char * error_table[EILSEQ - EPERM + 1] =
+static const char * error_table[ENOTSUP - EPERM + 1] =
 {
 	"Operation not permitted",
 	"No such file or directory",
@@ -127,7 +127,8 @@ static const char * error_table[EILSEQ - EPERM + 1] =
 	"Identifier removed",
 	"No message of the desired type.",
 	"Value too large to be stored in data type.",
-	"Encoding error detected"
+	"Encoding error detected",
+	"Not supported"
 };
 
 /****************************************************************************/
@@ -139,7 +140,7 @@ strerror_r(int number,char * buffer,size_t buffer_size)
 	const char * str;
 	size_t len;
 
-	if(number < EPERM || number > EILSEQ)
+	if(number < EPERM || number > ENOTSUP)
 	{
 		__set_errno(EINVAL);
 		goto out;