# must fail: receipts_index_257_claims
# an index listing more than 256 claims read (receipts::ReceiptIndex::from_bytes)
diff --git a/wai/wai-rs/src/http_binding/receipts.rs b/wai/wai-rs/src/http_binding/receipts.rs
index f2bdba57..9a891749 100644
--- a/wai/wai-rs/src/http_binding/receipts.rs
+++ b/wai/wai-rs/src/http_binding/receipts.rs
@@ -318,7 +318,7 @@ impl ReceiptIndex {
         if delivery.len() > MAX_INDEX_ITEMS {
             return Err(ReceiptRefusal::IndexTooLarge("more delivery items than a client reads"));
         }
-        if claims.len() > MAX_INDEX_CLAIMS {
+        if claims.len() > usize::MAX - MAX_INDEX_CLAIMS {
             return Err(ReceiptRefusal::IndexTooLarge("more claims than a client reads"));
         }
         Ok(ReceiptIndex {