diff --git a/src/hfround.mjs b/src/hfround.mjs
index 9276114b..8f975962 100644
--- a/src/hfround.mjs
+++ b/src/hfround.mjs
@@ -6,6 +6,10 @@ import { convertToNumber, roundToFloat16Bits } from "./helper/converter.mjs";
  * @returns {number}
  */
 export function hfround(num) {
+  if (typeof num === "bigint") {
+    throw TypeError("Cannot convert a BigInt value to a number");
+  }
+
   num = Number(num);
 
   // for optimization
diff --git a/test/hfround.js b/test/hfround.js
index 3394818a..4355a439 100644
--- a/test/hfround.js
+++ b/test/hfround.js
@@ -1,4 +1,4 @@
-/* eslint-env mocha */
+/* eslint-env mocha, es2020 */
 /* global assert hfround */
 
 describe("hfround()", () => {
@@ -64,4 +64,13 @@ describe("hfround()", () => {
   it("return 1.3369140625 when value is 1.337", () => {
     assert( hfround(1.337) === 1.3369140625 );
   });
+
+  it("throw TypeError when value is bigint", function () {
+    // Safari 13 doesn't have BigInt
+    if (typeof BigInt === "undefined") {
+      this.skip();
+    }
+
+    assert.throws(() => { hfround(BigInt(0)); }, TypeError);
+  });
 });