# must fail: head_proof_ok_OH
# covered subtrees are hashed with chunk counter 0 (head_proof::node_cv)
diff --git a/wai/wai-rs/src/http_binding/head_proof.rs b/wai/wai-rs/src/http_binding/head_proof.rs
index 40b6f1fa..d13bcdac 100644
--- a/wai/wai-rs/src/http_binding/head_proof.rs
+++ b/wai/wai-rs/src/http_binding/head_proof.rs
@@ -66,7 +66,7 @@ fn node_cv(
     if start >= c {
         it.next().ok_or(RangeRefusal::HeadProofMismatch)
     } else if start + len <= c {
-        Ok(subtree_cv(&x_prefix[start as usize..(start + len) as usize], start))
+        Ok(subtree_cv(&x_prefix[start as usize..(start + len) as usize], 0))
     } else {
         let l = left_len(len);
         let left = node_cv(x_prefix, start, l, c, it)?;