diff --git a/lib/stringify.js b/lib/stringify.js
index a2dea7e..62a179d 100644
--- a/lib/stringify.js
+++ b/lib/stringify.js
@@ -11,7 +11,7 @@ function getAsPrimitive(value) {
   } else if (type === "bigint" || type === "boolean") {
     return "" + value;
   } else if (type === "number" && Number.isFinite(value)) {
-    return value < 1e21 ? "" + value : encodeString("" + value);
+    return Math.abs(value) < 1e21 ? "" + value : encodeString("" + value);
   }
 
   return "";
diff --git a/test/stringify.test.ts b/test/stringify.test.ts
index dd3980a..2c0c6cb 100644
--- a/test/stringify.test.ts
+++ b/test/stringify.test.ts
@@ -94,6 +94,7 @@ test("should coerce numbers to string", () => {
   assert.strictEqual(qs.stringify({ foo: -72.42 }), "foo=-72.42");
   assert.strictEqual(qs.stringify({ foo: Number.NaN }), "foo=");
   assert.strictEqual(qs.stringify({ foo: 1e21 }), "foo=1e%2B21");
+  assert.strictEqual(qs.stringify({ foo: -1e21 }), "foo=-1e%2B21");
   assert.strictEqual(qs.stringify({ foo: Number.POSITIVE_INFINITY }), "foo=");
 });