diff --git a/crates/ourios-bench/tests/rfc0031_comparative.rs b/crates/ourios-bench/tests/rfc0031_comparative.rs
index 0bd0a7c55..f3a2d66e3 100644
--- a/crates/ourios-bench/tests/rfc0031_comparative.rs
+++ b/crates/ourios-bench/tests/rfc0031_comparative.rs
@@ -858,6 +858,17 @@ fn rfc0031_indicative_comparative_run() {
             "-distributor.ingestion-burst-size-mb=1024",
             "-ingester.per-stream-rate-limit=512MB",
             "-ingester.per-stream-rate-limit-burst=1GB",
+            // Runs #2–#4 all failed on the SAME ~5.27 MB internal message
+            // regardless of our batch size (3 MiB → 1.5 MB outer), proving
+            // a single `kafka`-service LogsData line's content alone
+            // inflates past the stock 4 MiB internal gRPC cap. Raising the
+            // cap (standard operator tuning, in Loki's favour — it lets
+            // Loki accept the data at all) preserves the identical-ingest
+            // precondition the equivalence check requires; skipping the
+            // line would silently unequalize the two corpora. Flag names
+            // per dskit's server registry (grpc_server_max_*_msg_size).
+            "-server.grpc-max-recv-msg-size-bytes=16777216",
+            "-server.grpc-max-send-msg-size-bytes=16777216",
         ])
         .await;
         push_corpus_to_loki(&http, &base, &corpus_dir).await;