From 89d97cfaa5f63f55ccb0fd27d9a45b61d63a9193 Mon Sep 17 00:00:00 2001
From: xiehuanyi <74809554+xiehuanyi@users.noreply.github.com>
Date: Sat, 10 Oct 2026 20:30:00 +0300
Subject: [PATCH] Use an unscaled formatter for a zero SI-prefix reference

AI-assisted implementation and verification using OpenAI Codex.
---
 src/locale.js             | 2 +-
 test/formatPrefix-test.js | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/locale.js b/src/locale.js
index 7a40df5..93e51a9 100644
--- a/src/locale.js
+++ b/src/locale.js
@@ -132,7 +132,7 @@ export default function(locale) {
   }
 
   function formatPrefix(specifier, value) {
-    var e = Math.max(-8, Math.min(8, Math.floor(exponent(value) / 3))) * 3,
+    var e = value === 0 ? 0 : Math.max(-8, Math.min(8, Math.floor(exponent(value) / 3))) * 3,
         k = Math.pow(10, -e),
         f = newFormat((specifier = formatSpecifier(specifier), specifier.type = "f", specifier), {suffix: prefixes[8 + e / 3]});
     return function(value) {
diff --git a/test/formatPrefix-test.js b/test/formatPrefix-test.js
index 69308ef..a9ce489 100644
--- a/test/formatPrefix-test.js
+++ b/test/formatPrefix-test.js
@@ -37,3 +37,11 @@ test("formatPrefix(\"($~s\", value)(number) formats with the SI prefix inside pa
   assert.strictEqual(formatPrefix("($~s", 1e3)(1e3), "$1k");
   assert.strictEqual(formatPrefix("($~s", 1e3)(-1e3), "($1k)");
 });
+
+test("formatPrefix uses no SI prefix for a zero reference value", () => {
+  const f = formatPrefix(".1", 0);
+  assert.strictEqual(f(0), "0.0");
+  assert.strictEqual(f(1), "1.0");
+  assert.strictEqual(f(-1), "−1.0");
+  assert.strictEqual(formatPrefix(".1", -0)(1), "1.0");
+});