diff --git a/include/mbedtls/nist_kw.h b/include/mbedtls/nist_kw.h
index 3b67b59..c94c15a 100644
--- a/include/mbedtls/nist_kw.h
+++ b/include/mbedtls/nist_kw.h
@@ -133,6 +133,7 @@
  *
  * \return          \c 0 on success.
  * \return          \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length.
+ * \return          \c MBEDTLS_ERR_PLATFORM_ALLOC_FAILED in case of a memory allocation failure.
  * \return          cipher-specific error code on failure of the underlying cipher.
  */
 int mbedtls_nist_kw_wrap( mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode,