diff --git a/tests/corpus-node-islands-order/g05-zlib/main.ts b/tests/corpus-node-islands-order/g05-zlib/main.ts
index 14abe51b1..3a4c9fac9 100644
--- a/tests/corpus-node-islands-order/g05-zlib/main.ts
+++ b/tests/corpus-node-islands-order/g05-zlib/main.ts
@@ -1,4 +1,5 @@
 // @requires-libnode
+// @order: race
 // X { T 0 { Z { L i-zlib } } } T 2 { B 80 L h-sync }
 import { callSync } from "@scriptc/node";
 import { readFile, writeSync } from "node:fs";
diff --git a/tests/harness/node-island-order.test.ts b/tests/harness/node-island-order.test.ts
index 5d4aa96a1..1f86babac 100644
--- a/tests/harness/node-island-order.test.ts
+++ b/tests/harness/node-island-order.test.ts
@@ -13,7 +13,9 @@
  * A program whose head says `// @order: race` races a timer against I/O
  * whose duration differs between the sides (scriptc's own fs callbacks
  * complete in one turn where Node's readFile takes several; module loading
- * on the first call into Node takes longer than in a Node process), or two
+ * on the first call into Node takes longer than in a Node process; a job on
+ * libuv's thread pool, such as zlib's, can finish before or after a 2 ms
+ * timer depending on the host), or two
  * equal timers armed on either side of an island call, which a millisecond
  * boundary between them (likely in a sanitized build) puts in different
  * loop turns, so Node permits orders it rarely produces in M runs. Its