diff --git a/src/testcurl/test_digestauth.c b/src/testcurl/test_digestauth.c
index 04a3995d..93f79a6a 100644
--- a/src/testcurl/test_digestauth.c
+++ b/src/testcurl/test_digestauth.c
@@ -245,7 +245,7 @@ ahc_echo (void *cls,
                                   password,
                                   300,
                                   MHD_DIGEST_ALG_MD5);
-  free (username);
+  MHD_free (username);
   if ( (ret_i == MHD_INVALID_NONCE) ||
        (ret_i == MHD_NO) )
   {