diff --git a/src/include/microhttpd.h b/src/include/microhttpd.h
index 6b749477..e7d8bf52 100644
--- a/src/include/microhttpd.h
+++ b/src/include/microhttpd.h
@@ -3117,6 +3117,7 @@ MHD_digest_auth_get_username (struct MHD_Connection *connection);
  * Free the memory given by @a ptr. Calls "free(ptr)".  This function
  * should be used to free the username returned by
  * #MHD_digest_auth_get_username().
+ * @note Since v0.9.56
  *
  * @param ptr pointer to free.
  */
diff --git a/src/microhttpd/digestauth.c b/src/microhttpd/digestauth.c
index ace3cdc2..509652e8 100644
--- a/src/microhttpd/digestauth.c
+++ b/src/microhttpd/digestauth.c
@@ -462,6 +462,7 @@ check_nonce_nc (struct MHD_Connection *connection,
  * @param connection The MHD connection structure
  * @return NULL if no username could be found, a pointer
  * 			to the username if found
+ * @warning Returned value must be freed by #MHD_free().
  * @ingroup authentication
  */
 char *
diff --git a/src/microhttpd/memorypool.c b/src/microhttpd/memorypool.c
index 163aa4e3..bda45e1e 100644
--- a/src/microhttpd/memorypool.c
+++ b/src/microhttpd/memorypool.c
@@ -81,10 +81,11 @@ struct MemoryPool
  * Free the memory given by @a ptr. Calls "free(ptr)".  This function
  * should be used to free the username returned by
  * #MHD_digest_auth_get_username().
+ * @note Since v0.9.56
  *
  * @param ptr pointer to free.
  */
-void
+_MHD_EXTERN void
 MHD_free (void *ptr)
 {
   free (ptr);