diff --git a/polyfill/polyfill.mjs b/polyfill/polyfill.mjs
index 1b523dd..ca05770 100644
--- a/polyfill/polyfill.mjs
+++ b/polyfill/polyfill.mjs
@@ -55,7 +55,7 @@ export function sum(iterable) {
     }
     if (!Object.is(value, -0)) {
       if (!Number.isFinite(value)) {
-        return drainNonFiniteValue(val);
+        return drainNonFiniteValue(value);
       }
       partials.push(value);
       break;
diff --git a/polyfill/test-polyfill.mjs b/polyfill/test-polyfill.mjs
index 9a01a11..3c2c2d8 100644
--- a/polyfill/test-polyfill.mjs
+++ b/polyfill/test-polyfill.mjs
@@ -43,6 +43,9 @@ test('special cases', t => {
   assert.strictEqual(mathSum([-0, -0, -0, 0]), 0);
   assert.strictEqual(mathSum([1, Infinity, -1e308]), Infinity);
   assert.strictEqual(mathSum([1, Infinity, -1e308, -Infinity]), NaN);
+  assert.strictEqual(mathSum([Infinity]), Infinity);
+  assert.strictEqual(mathSum([-Infinity]), -Infinity);
+  assert.strictEqual(mathSum([-Infinity, Infinity]), NaN);
 });
 
 test('1, 2 element lists', t => {