diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h
index 3bc675e..146367b 100644
--- a/include/mbedtls/hmac_drbg.h
+++ b/include/mbedtls/hmac_drbg.h
@@ -195,10 +195,13 @@
  * \param additional    Additional data to update state with, or NULL
  * \param add_len       Length of additional data, or 0
  *
+ * \return              \c 0 on success, or an error from the underlying
+ *                      hash calculation.
+ *
  * \note                Additional data is optional, pass NULL and 0 as second
  *                      third argument if no additional data is being used.
  */
-void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx,
+int mbedtls_hmac_drbg_update_ret( mbedtls_hmac_drbg_context *ctx,
                        const unsigned char *additional, size_t add_len );
 
 /**
@@ -257,6 +260,31 @@
  */
 void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx );
 
+#if ! defined(MBEDTLS_DEPRECATED_REMOVED)
+#if defined(MBEDTLS_DEPRECATED_WARNING)
+#define MBEDTLS_DEPRECATED    __attribute__((deprecated))
+#else
+#define MBEDTLS_DEPRECATED
+#endif
+/**
+ * \brief               HMAC_DRBG update state
+ *
+ * \deprecated          Superseded by mbedtls_hmac_drbg_update_ret()
+ *                      in 2.16.0.
+ *
+ * \param ctx           HMAC_DRBG context
+ * \param additional    Additional data to update state with, or NULL
+ * \param add_len       Length of additional data, or 0
+ *
+ * \note                Additional data is optional, pass NULL and 0 as second
+ *                      third argument if no additional data is being used.
+ */
+MBEDTLS_DEPRECATED void mbedtls_hmac_drbg_update(
+    mbedtls_hmac_drbg_context *ctx,
+    const unsigned char *additional, size_t add_len );
+#undef MBEDTLS_DEPRECATED
+#endif /* !MBEDTLS_DEPRECATED_REMOVED */
+
 #if defined(MBEDTLS_FS_IO)
 /**
  * \brief               Write a seed file