diff --git a/src/gss_sec_ctx.c b/src/gss_sec_ctx.c
index aef4246..3ddc38b 100644
--- a/src/gss_sec_ctx.c
+++ b/src/gss_sec_ctx.c
@@ -756,7 +756,8 @@ uint32_t gssntlm_accept_sec_context(uint32_t *minor_status,
                                          nb_domain_name,
                                          server_name->data.server.name,
                                          NULL, NULL,
-                                         &av_flags, &timestamp,
+                                         av_flags ? &av_flags : NULL, /* don't include empty MsvAvFlags */
+                                         &timestamp,
                                          NULL,
                                          server_name->data.server.spn,
                                          NULL,