Add FEATURE_NOT_AVAILABLE error codes.
diff --git a/include/mbedtls/chacha20.h b/include/mbedtls/chacha20.h
index 579ea38..7a8cd53 100644
--- a/include/mbedtls/chacha20.h
+++ b/include/mbedtls/chacha20.h
@@ -42,7 +42,8 @@
#include <stdint.h>
#include <stddef.h>
-#define MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA -0x003B /**< Invalid input parameter(s). */
+#define MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA -0x0053 /**< Invalid input parameter(s). */
+#define MBEDTLS_ERR_CHACHA20_FEATURE_UNAVAILABLE -0x0055 /**< Feature not available. For example, s part of the API is not implemented. */
#ifdef __cplusplus
extern "C" {