# must fail: receipts_file_too_large receipts_parent_too_large
# a receipt file over 1 MiB read (receipts::ReceiptFetcher::get)
diff --git a/wai/wai-rs/src/http_binding/receipts.rs b/wai/wai-rs/src/http_binding/receipts.rs
index 83cd7ccb..822b9975 100644
--- a/wai/wai-rs/src/http_binding/receipts.rs
+++ b/wai/wai-rs/src/http_binding/receipts.rs
@@ -307,7 +307,7 @@ impl<'f> ReceiptFetcher<'f> {
         match &self.memo[h] {
             Served::Nothing => Err(ReceiptRefusal::NotServed),
             Served::PastBytes => Err(ReceiptRefusal::BytesExhausted),
-            Served::Bytes(b) if b.len() > MAX_RECEIPT_FILE_BYTES => Err(ReceiptRefusal::TooLarge),
+            Served::Bytes(b) if b.len() > usize::MAX - MAX_RECEIPT_FILE_BYTES => Err(ReceiptRefusal::TooLarge),
             Served::Bytes(b) => Ok(b.clone()),
         }
     }