# must fail: fetch_O3_proof_unanswered
# an unanswered base is reported as a malformed head (session::drive)
diff --git a/wai/wai-rs/src/http_binding/session.rs b/wai/wai-rs/src/http_binding/session.rs
index 4730c192..9ba8287a 100644
--- a/wai/wai-rs/src/http_binding/session.rs
+++ b/wai/wai-rs/src/http_binding/session.rs
@@ -802,7 +802,7 @@ pub fn drive(
             }
             if session.queued.is_empty() {
                 if session.outstanding() > 0 {
-                    return Err(RangeRefusal::BaseUnanswered);
+                    return Err(RangeRefusal::HeadMalformed("unanswered".into()));
                 }
                 return Err(RangeRefusal::HeadMalformed("the session wants nothing and has no outcome".into()));
             }