diff --git a/src/format.test.ts b/src/format.test.ts
index cdabb0f..3d793d1 100644
--- a/src/format.test.ts
+++ b/src/format.test.ts
@@ -258,4 +258,16 @@ describe('format(invalid inputs)', () => {
       format(-Infinity);
     }).toThrow();
   });
+
+  it('should handle negative pluralization correctly', () => {
+    expect(format(-1500, { long: true })).toBe('-1 second');
+    expect(format(-1501, { long: true })).toBe('-2 seconds');
+    expect(format(-1000, { long: true })).toBe('-1 second');
+  });
+
+  it('should handle positive pluralization correctly', () => {
+    expect(format(1500, { long: true })).toBe('2 seconds');
+    expect(format(1501, { long: true })).toBe('2 seconds');
+    expect(format(1000, { long: true })).toBe('1 second');
+  });
 });
diff --git a/src/index.ts b/src/index.ts
index d50e3c7..b1f3df5 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -239,6 +239,7 @@ function plural(
   n: number,
   name: string,
 ): StringValue {
-  const isPlural = msAbs >= n * 1.5;
-  return `${Math.round(ms / n)} ${name}${isPlural ? 's' : ''}` as StringValue;
+  const rounded = Math.round(ms / n);
+  const isPlural = Math.abs(rounded) !== 1;
+  return `${rounded} ${name}${isPlural ? 's' : ''}` as StringValue;
 }