diff --git a/tests/harness/npm.test.ts b/tests/harness/npm.test.ts
index 13ad3f438..9a13c0968 100644
--- a/tests/harness/npm.test.ts
+++ b/tests/harness/npm.test.ts
@@ -112,10 +112,15 @@ const KNOWN: Record<string, Known> = {
 const cases = shardSelect(npmCases(fixturesRoot), (c) => c.name);
 
 /** Per-case timeouts past the default 120 s: the undici cases compile the
- * built-in undici implementation's module graph, and zod3 compiles zod 3's
- * 3,700-line types module. A sanitized build of either takes minutes on a
- * CI runner. */
-const TIMEOUTS: Record<string, number> = { undici5: 600_000, undici7: 600_000, zod3: 600_000 };
+ * built-in undici implementation's module graph, and zod3 and zod3-infer
+ * compile zod 3's 3,700-line types module. A sanitized build of either
+ * takes minutes on a CI runner. */
+const TIMEOUTS: Record<string, number> = {
+  undici5: 600_000,
+  undici7: 600_000,
+  zod3: 600_000,
+  "zod3-infer": 600_000,
+};
 
 interface RunResult {
   stdout: Buffer;