diff --git a/src/defs/types.ts b/src/defs/types.ts
index 3e9edb5..cd601d8 100644
--- a/src/defs/types.ts
+++ b/src/defs/types.ts
@@ -39,7 +39,7 @@ export function paramNumber(value: ParamValue | undefined, fallback: number): nu
 }
 
 /** Spells a refused value for the caller who wrote it; JSON spells NaN and the infinities `null`. */
-export function valueText(value: unknown): string {
+export function valueText(value: ParamValue): string {
 	return typeof value === 'number' ? String(value) : JSON.stringify(value);
 }
 
diff --git a/test/types.test.ts b/test/types.test.ts
index c55cc86..c855106 100644
--- a/test/types.test.ts
+++ b/test/types.test.ts
@@ -42,7 +42,6 @@ describe('integers', () => {
 
 		const notANumber = types.int8.write(NaN, Buffer.alloc(1), 0);
 
-		// JSON spells NaN and the infinities `null`, which is a value the caller never wrote.
 		assert.ok(notANumber.err instanceof Error);
 		assert.match(notANumber.err.message, /NaN/);
 	});
diff --git a/todo.md b/todo.md
index 4577653..9d6f8b3 100644
--- a/todo.md
+++ b/todo.md
@@ -419,7 +419,8 @@ and is also what the panel ranked hardest — two methods, one answer.
       `idleTimeout: '5000'` is refused with `got 5000` — a value the reader reads as correct — where
       `connectTimeout` quotes it. `namedValue()`'s four sites — `messagingMode`, `encoding`, the time
       options and `smsIdFormat` — are the same defect once more: there `true` and `'true'` both print
-      as `true`. One fix closes all three. Raised by review, 2026-09-20.
+      as `true`. One fix closes all three, and `valueText()` in `defs/types.ts` is the quoted
+      spelling to take it from. Raised by review, 2026-09-20.
 
 - [ ] **A send the codec will refuse waits for a link and a window slot first.** `refuse()` in
       `outgoing-requests.ts` runs `misuse()` and the abort check before the wait, precisely so a call